Australian Curriculum Science: Year 6 - Ages 11-12

RIC-6699 4.5/1230

Australian curriculum science (Year 6) Published by R.I.C. Publications® 2011 Copyright© R.I.C. Publications® 2011 ISBN 978-1-74126-993-2 RIC– 6699

Copyright Notice

Titles in this series: Australian curriculum science (Foundation) Australian curriculum science (Year 1) Australian curriculum science (Year 2) Australian curriculum science (Year 3) Australian curriculum science (Year 4) Australian curriculum science (Year 5) Australian curriculum science (Year 6) Australian curriculum science (Year 7)

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This master may only be reproduced by the original purchaser for use with their class(es). The publisher prohibits the loaning or onselling of this master for the purposes of reproduction.

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Internet websites In some cases, websites or specific URLs may be recommended. While these are checked and rechecked at the time of publication, the publisher has no control over any subsequent changes which may be made to webpages. It is strongly recommended that the class teacher checks all URLs before allowing students to access them.

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Website: www.ricpublications.com.au Email: mail@ricgroup.com.au

Foreword Australian curriculum science – Foundation to Year 7 is a series of books written specifically to support the national curriculum. Science literacy texts introduce concepts and are supported by practical hands-on activities, predominantly experiments.

All Science Understanding and Science as a Human Endeavour substrands for each level are included. Science inquiry skills and overarching ideas underpin all topics.

Australian curriculum science is a complementary resource to the previously released R.I.C. series, Primary Science.

r o e t s Bo r e p ok u S Contents

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Titles in this series are: Australian curriculum science – Foundation Australian curriculum science – Year 1 Australian curriculum science – Year 2 Australian curriculum science – Year 3 Australian curriculum science – Year 4 Australian curriculum science – Year 5 Australian curriculum science – Year 6 Australian curriculum science – Year 7

Teachers notes ................................................................... iv–vi

How are earthquakes and tsunamis related?.....................42–44

Science inquiry skills overview ................................................vii

How submarine earthquakes can create tsunamis .................. 45

Scientific method ...................................................................viii

How are earthquakes measured?......................................46–48

Investigation format ................................................................ ix

Earthquake research .............................................................. 49

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How are volcanic eruptions monitored? ...........................50–52

Biological sciences .........................................................2–17

Ring of Fire eruptions ............................................................ 53

How important is soil?..........................................................2–4

What are the effects of drought? .......................................54–56

Best conditions for growth ....................................................... 5

Clean water for all! ................................................................. 57

What are fungi and what do they do? ....................................6–8 Why do plants and animals need to adapt? .......................10–12

How does electricity flow? ................................................58–60

Plant and animal adaptations ................................................. 13

Connecting circuits ................................................................ 61

Why do animals migrate or hibernate? .............................14–16

What are electrical conductors and insulators? ................62–64

Migration and hibernation ..................................................... 17

Conductor or insulator? ......................................................... 65

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Physical sciences ..........................................................58–81

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Foul fungi................................................................................. 9

How do light globes work? ...............................................66–68

Chemical sciences ........................................................18–37

Electromagnetism unplugged! ................................................ 69

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What happens when materials are mixed? ........................18–20

How do wind and water generate electricity? ....................70–72

Clean dirty water .................................................................... 21

Making the most of water power ............................................ 73

What is solubility?.............................................................22–24

How do we get power from the sun?.................................74–76

The effect of particle size and stirring on solubility................. 25

Solar-powered pathways......................................................... 77

What changes do heating and cooling cause? ...................26–28

Which energy sources for the future? ...............................78–80

Just add salt! .......................................................................... 29

Sustainable energy sources on tap.......................................... 81

Why do metals rust? .........................................................30–32 Rusting nails .......................................................................... 33 How is reversible change used in recycling? .....................34–36 Recycling paper ..................................................................... 37 Earth and space sciences ..............................................38–57 What causes a volcanic eruption? .....................................38–40 Create the most explosive volcano .......................................... 41

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Teachers notes Each book is divided into four sections corresponding to the four substrands of the Science Understanding strand of the curriculum. Shaded tabs down the side of each book provide a quick and easy means to locate biological sciences, chemical sciences, Earth and space sciences or physical sciences substrands.

Science as a Human Endeavour units or questions, as set out in the Australian Curriculum, are included in all substrands.

Science inquiry skills are included in all units. The skills utilised are listed on each teachers page.

The six overarching ideas (Patterns, order and organisation; Form and function; Stability and change; Scale and measurement; Matter and energy; and Systems) underpin each science literacy text page and are included as much as possible throughout the comprehension pages.

Each substrand is divided into a number of four-page units, each covering a particular aspect and following a consistent format.

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The four-page format of each unit consists of: • a teachers page

• student page 1, which is a science literacy text about the concept with relevant diagrams or artwork

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• student page 2, which includes comprehension questions about the literacy text • student page 3, which involves a hands-on activity such as an experiment.

Teachers page

The first page in each four-page format is a teachers page which provides the following information:

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FOUR-PAGE FORMAT

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• A shaded tab gives the Science Understanding substrand.

• The title of the four-page unit is given.

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• The inquiry skills focus covered within the four pages is set out.

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• The content focus (the particular aspect of the unit covered in that set of four pages) is given.

• Answers and explanations are provided where appropriate for student pages 2 and 3 (the comprehension questions relating to the text and the final activity in the set of four pages).

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• Preparation states any material or resources the teacher may need to collect to implement a lesson, or carry out an experiment or activity.

• The lessons provides information relating to implementing the lessons on the following student pages.

• Background information, which includes additional information for teacher and student use and useful websites relating to the topic of the section, expands on the unit.

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Teachers notes FOUR-PAGE FORMAT (continued) Student page 1 The second page in the four-page format is a science literacy text which introduces the topic. This page provides the following information:

• A shaded tab down the side gives the Science Understanding substrand.

Fungi are strange organisms. They are neither plant nor animal but are similar to both. They can be so tiny that a microscope is needed to see them or so large that they can be seen from a distance. Mushrooms are fungi. You can eat some, like button and oyster, but others, like death cap and destroying angel, can kill you. Some fungi can cure infections (from penicillium comes the penicillin antibiotic) and others can cause them (yeast infections such as tinea and ringworm). Fungi exist in all varieties of environment: in air, soil and water.

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• The title of the unit is given. This is in the form of a question to incorporate science inquiry skills and overarching ideas.

Some cheeses are mould ripened. The mould produces a substance that works on the cheese to produce a flavour and smell.

The longer the cheese is left, the stronger the flavour becomes. Brie and camembert are coated with a fine layer of white mould and the flavour develops from the outside in.

This is called surface ripening. Stilton and Danish blue are injected with blue mould and the flavour develops from the inside.

Unlike green plants, fungi do not need sunlight to grow. They obtain their food from dead organic matter or they live as parasites on living flesh. Fungi are important in all food webs. As they feed, they produce substances called enzymes which break down the organic matter, releasing energy back into the soil in the form of nutrients. Fungi grow best in damp, warm conditions.

• The science literacy text is provided.

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Moulds and yeasts are types of fungi. They can destroy food. Mould will grow on any moist food item that is left long enough in warm conditions. But some yeasts and moulds are vital in the production of many foods and beverages; for example, yeasts can act on the sugar in canned soft drinks and form carbon dioxide.

Biological sciences

What are fungi and what do they do? – 1

Without yeast, bread could not rise and fruit and cereal grain could not ferment to produce wine and beer.

Yeast works in two ways: With air, the yeast converts sugar to carbon dioxide. This process is called respiration. With little or no air, sugar is converted to alcohol and carbon dioxide. This process is called fermentation.

In bread making, both processes occur.

Carbon dioxide from respiration causes the dough to rise and fermentation produces the delicious smell. The alcohol that is produced in dough is destroyed during baking.

• Relevant diagrams or artwork enhance the text, or are used to assist student understanding of the concepts.

In the production of soy sauce, first a mould is added to break down the soy beans into a paste. A yeast then feeds on the paste and in doing so produces a liquid with desirable flavours. After about a month, the liquid is ready to be separated, sterilised to kill the yeasts and moulds, and bottled ready for sale as soy sauce.

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Student page 2

The second student page consists of a series of questions or activities relating to the literacy text. They aim to gauge student understanding of the concepts presented in the text. Many of these questions relate to overarching ideas relevant to that age level as stated in the Australian Curriculum Science.

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• The title, which is the same as the text page, is given.

• A shaded tab gives the Science Understanding substrand.

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• Questions or activities follow. These relate to the text on the previous page.

Where relevant, a question relating to Science as a Human Endeavour may be included as the final question on this page.

This assists in keeping the strands interrelated. This question is indicated by the icon shown to the left.

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Teachers notes FOUR-PAGE FORMAT (continued) Student page 3 The third student page provides a hands-on activity. It may be an experiment, art or craft activity, research activity or similar.

• A shaded tab gives the Science Understanding substrand.

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• The title is given. This will be different from the previous two pages, but will be a related to the concept focus of the unit.

• An adapted procedure for an experiment, craft activity or a research activity is given.

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Science as a Human Endeavour units and questions

Those four-page units which are related specifically to Science as a Human Endeavour substrands are indicated by the icon shown.

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Where Science as a Human Endeavour questions occur within Science Understanding units, they are also indicated by the use of the icon. Explanations and answers relating to these questions are given on the appropriate teachers page.

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Science inquiry skills overview Biological sciences PAGES

Questioning and predicting

Planning and conducting

Processing and analysing data and information

Evaluating

Communicating

2–5 6–9 10–13 14–17

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Planning and conducting

Processing and analysing data and information

18–21

22–25 26–29

30–33 34–37

PAGES

Evaluating

Communicating

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Questioning and predicting

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Questioning and predicting

Planning and conducting

Processing and analysing data and information

Evaluating

Communicating

38–41

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42–45 46–49 50–53

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PAGES

Questioning and predicting

58–61

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Planning and conducting

Processing and analysing data and information

Evaluating

Communicating

62–65 66–69 70–73 74–77 78–81

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Scientific method Subject Question

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Background research

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Hypothesise

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Analyse data

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Test hypothesis

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Communicate results

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Investigation format Title (What am I investigating?)

Prediction (What do I expect to discover?)

Procedure

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Equipment

(What do I need?

How do I use it?)

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(How am I going to set up the investigation?)

Reliability

(How will I ensure a fair test?)

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Observations/Measurements (How will I record what I see and/or measure?)

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Analysis of results

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(What do my results show?

How do they relate to my prediction?)

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Developing explanations (What do my results mean?)

Communicating

(How will I present my results?)

Reflecting on methods (How effective was my method for this investigation?

How would I change the method to provide more meaningful data?)

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How important is soil?

Inquiry skills focus:

Answers

Different soils and the effect of salinity on fertility

Page 4 1. (a) Weathered rock particles and living and decayed organic matter (b) stability, water, nutrients 2. (a) By the type of rock it comes from and the size of rock particles in it. (b) How much air and water it can hold; if it is acidic or alkaline.

3. Plants grow better in fertilised soil but fertiliser can be washed into waterways causing an algal bloom.

4. Teacher check: Groundwater – the water present underground; Watertable – how far the level of the underground water is below the surface.

5. (a) They grow deep into the soil, taking up lots of groundwater, keeping the groundwater level from rising. (b) They do not grow very deep and they use much less underground water, especially when watered from above.

6. (a) Salt is present in the ground and dissolves in the groundwater as the level of the watertable rises. (b) Salt makes it more difficult for roots to take up water. This causes plants to dehydrate. Salt that does get into the plant can not get out again and damages the cells of the plant. (c) Most plants can not tolerate a high level of salt and so will not be able to grow and survive in soil with a very high salt content.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Useful websites: − <http://www.kidsgeo.com/geology-for-kids/0002-the-earths-soil. php> − <http://encyclopedia.kids.net.au/page/so/Soil> − <http://www.soil-net.com/> Preparation

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• For the activity on page 5, provide: sets of plants in seedling trays; salt and water; a measuring jug; kitchen spoon measuring set; stirrers; mini plastic plant pots; compost; measuring cup (1/3 cup).

Page 5

Students will discover that as the concentration of salt increases, the growth of the plant diminishes. In their evaluations, students could consider altering the concentration levels if they were to repeat the investigation. If all plants die, then even the lowest concentration was too much and more dilute solutions must be made. If all plants thrive, then more concentrated solutions must be made.

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• The students need to understand that in any experiment a control or control group is needed. The control is the object, material or substance that nothing is done to; it remains the same (unchanged) and serves as the standard (or blank state) that the other objects, materials or substances are compared to.

The lessons

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• If the concentration of salt outside the plant is greater than that inside it, water leaves the plant in an effort to equalise the concentration.

This causes dehydration. Mangrove trees can tolerate higher levels of salt in water as their cells already have a high concentration of salt in them. Many herbicides use this principle to destroy plants.

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Content focus:

• Pages 3 and 4 should be used together.

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• For the investigation on page 5, the class can be divided into any number of groups with each group following the same investigation but with a different plant. The ‘Before you begin’ questions can be discussed within groups but may need to be standardised before the investigation starts.

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• For the investigation on page 5, if each group is given a different plant to work with, the class as a whole can also determine which plant is the most/least salt tolerant. For this, the concentrations of the salt solutions must be the same among all groups. These can be made by using a standard kitchen spoon measuring set and adding 1 /4 teaspoon, 1/2 teaspoon, 1 teaspoon and 1 tablespoon of salt to cups of 250 mL of water. An equal amount of plain water should be used for the control. To ensure a fair test, the plants should receive equal amounts of watering solution at each watering. Transfer the seedlings to small flower pots and add equal quantities of compost to each for stability. All test plants must be located in the same place.

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Soil is the thin layer of weathered rock particles and living and decayed organic matter that covers the surface of the Earth. It is in which plant roots anchor themselves, giving the plant stability, and providing water and nutrients. The decision of what are the best plants to grow in a certain area is usually determined by the available soil.

Soil types clay

from sedimentary rocks

sandy

from limestone, granite, quartz, shale

silty

contains quartz

loamy

mixture of sand, silt and clay

peaty

mostly organic matter, acidic

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In the world, there are six different soil types that exist. They are classified by the type of rock and size of the particles they contain. This affects how much air and water the soil can hold and how acidic or alkaline it is. The nutritional quality of the soil depends on how much organic matter is blended with the rock particles.

A type of plant may be able to grow in all low quality/often infertile chalky soils but will most likely grow best in one or two types of soil. Farmers and gardeners need to know which plants grow best in which soils. The nutritional quality of a soil can be improved by adding fertiliser.

When fertiliser is added to a soil, it can cause plants to grow very well. But when it rains, a nitrogen-rich fertiliser can leach into waterways and create an algal bloom (which destroys other water life).

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C.Publ i cat i ons Deep-rooted plants take up large amounts of groundwater and lose it to the atmosphere •f orr evi ew pur posesonl y• through evaporation and transpiration. This keeps the watertable low. Shallow-rooted,

When large plants with deep roots (such as trees) are cut down to make way for cultivating shallow-rooted plants, increased salinity can occur.

cultivated plants require far less water than trees, so the watertable rises. This would not be a problem if there was no salt in the soil.

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When the watertable rises, it dissolves the naturally-occurring salt in the ground, which then attacks plants in two ways. Firstly, it is more difficult for roots to take up water that contains salt, so the plant dies through lack of water. Secondly, the salt contained in the water the roots do take up remains in the plant, destroying the structure of its cells and causing the plant to die.

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Plants that grow in estuaries are more tolerant of the salt levels in sea water, but salinity from rising watertable levels (known as ‘dryland salinity’) can occur far from the sea where there are few, if any, salt-tolerant plants.

Increasing salinity is a worldwide environmental problem. A rising watertable transports more salt to the surface, making the soil less able to support life. The salt can be seen as white deposits on the surface of the ground.

A lot of water is lost through evaporation and transpiration.

Much less water is lost through evaporation and transpiration.

Shallow-rooted crops take up less water.

salts dispersed

watertable deep roots

watertable groundwater

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Biological sciences

How important is soil? – 1

How important is soil? – 2 1. (a) What does soil consist of?

(b) What does soil provide for the plants that grow in it?

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2. (a) How is a soil type classified?

(b) What are the main characteristics of a soil?

3. Describe the positive and negative effects of adding fertiliser to soil.

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5. (a) How do deep-rooted plants keep the watertable low?

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4.

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Biological sciences

Use the text on page 3 to complete the following.

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(b) How do shallow-rooted plants raise the watertable?

6. (a) Where does the salt in dryland salinity come from?

(b) How does salt destroy plants?

(c) How does salt reduce the fertility of soil?

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Plants can tolerate a range of different conditions, such as soil types and amount of direct sunlight and wind they recieve.

You will be given plants from the same batch to water with salt solutions of different strengths to determine the plant’s tolerance to salt.

Before you begin How will you ensure a fair test?

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What will be your control for the investigation?

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What strengths of salt solution will you use and how will you make them?

When, how often and how much will you water the plants?

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C.Publ i cat i ons o rr evi ew pur posesonl y• How often• andf by which way Where will you locate the plants?

will you observe the growth of the plants?

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How will you record your observations?

What do you predict will be the outcome of this investigation?

o c . che e r o t r s super At the end of the investigation

How did your results compare to your prediction?

What can you conclude from this investigation?

How do your results compare to other groups using different plants?

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Biological sciences

Best conditions for growth

What are fungi and what do they do?

Inquiry skills focus:

Answers

The behaviour of fungi and their role in food production and spoilage

Page 8 1. Teacher check; answers could include: they can be good or bad, big or small. They can kill or cure. They can destroy food or be important in producing food. They are a bit like plants and a bit like animals yet they are neither.

2. (a) They decompose dead organic matter. They feed as parasites on living flesh. (b) enzymes 3. (a) from the outside in (b) from the inside out 4. (a) In respiration, only carbon dioxide is produced. In fermentation, alcohol is also produced. (b) Respiration occurs in the presence of air. Fermentation occurs with little or no air.

5. (a) carbon dioxide produced during respiration (b) alcohol produced during fermentation 6. (a) Enzymes produced by the mould break down the beans into a paste. (b) Enzymes produced by the yeast break the paste down to a liquid and produce desirable flavours.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Fungi can grow in all but frozen conditions. They can exist in a dormant state as spores until conditions improve.

• Using beneficial fungi, scientists have developed pesticides that produce substances that are toxic to many insects and crop-destroying pests.

• Useful websites: − <http://www.northamptonshirewildlife.co.uk/nfungi/ fungiforkids.htm> − <http://encyclopedia.kids.net.au/page/fu/Fungi> − <http://www.biology4kids.com/files/micro_fungi.html> Preparation

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Teacher check Students will discover that fungi grow in all conditions except in freezing temperatures. The greatest growth occurs where conditions are warm and damp.

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• Bring in samples of mould-ripened cheeses and different varieties of bread that show different sized gas pockets, as well as ingredients and equipment for bread making. Also bring in (though keep covered) foods that have been spoiled by fungi; for example: bread, jam, cheese, fruit.

• Remind the students that a fair test is one in which only one variable is changed at a time; for example, when comparing the effects of light, water and air on two plants, only one of these factors (light, water or air) should change at a time.

The lessons

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• Common fungi include all types of mushrooms, yeasts and moulds.

They are essential in the breakdown of dead organic matter, converting it into nutrients for the soil.

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Biological sciences

Content focus:

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• Pages 7 and 8 should be used together.

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• If possible, demonstrate the process of bread making with students, making observations at all stages of the process. Show the difference between surface-ripened and veined cheeses. Compare the different foods spoiled by fungi.

• For the investigation on page 9, discuss possible foods and locations for samples; for example: fruits and vegetables in warm and dry/damp and cold conditions. Students should remember that all samples must be treated similarly.

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Moulds and yeasts are types of fungi. They can destroy food. Mould will grow on any moist food item that is left long enough in warm conditions. But some yeasts and moulds are vital in the production of many foods and beverages; for example, yeasts can act on the sugar in canned soft drinks and form carbon dioxide.

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Some cheeses are mould ripened. The mould produces a substance that works on the cheese to produce a flavour and smell.

The longer the cheese is left, the stronger the flavour becomes. Brie and camembert are coated with a fine layer of white mould and the flavour develops from the outside in.

This is called surface ripening. Stilton and Danish blue are injected with blue mould and the flavour develops from the inside.

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Teac he r

Fungi are strange organisms. They are neither plant nor animal but are similar to both. They can be so tiny that a microscope is needed to see them or so large that they can be seen from a distance. Mushrooms are fungi. You can eat some, like button and oyster, but others, like death cap and destroying angel, can kill you. Some fungi can cure infections (from penicillium comes the penicillin antibiotic) and others can cause them (yeast infections such as tinea and ringworm). Fungi exist in all varieties of environment: in air, soil and water.

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C.Publ i cat i ons •f orr evi ew pur posesonl y• Unlike green plants, fungi do not need

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Without yeast, bread could not rise and fruit and cereal grain could not ferment to produce wine and beer.

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sunlight to grow. They obtain their food from dead organic matter or they live as parasites on living flesh. Fungi are important in all food webs. As they feed, they produce substances called enzymes which break down the organic matter, releasing energy back into the soil in the form of nutrients. Fungi grow best in damp, warm conditions.

Yeast works in two ways. With air, the yeast converts sugar to carbon dioxide. This process is called respiration. With little or no air, sugar is converted to alcohol and carbon dioxide. This process is called fermentation.

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In bread making, both processes occur.

Carbon dioxide from respiration causes the dough to rise and fermentation produces the delicious smell. The alcohol that is produced in dough is destroyed during baking.

In the production of soy sauce, first a mould is added to break down the soy beans into a paste. A yeast then feeds on the paste and in doing so produces a liquid with desirable flavours. After about a month, the liquid is ready to be separated, sterilised to kill the yeasts and moulds, and bottled ready for sale as soy sauce.

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Biological sciences

What are fungi and what do they do? – 1

What are fungi and what do they do? – 2 1. In your own words, explain why fungi are strange organisms.

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2. (a) Fungi obtain food from two sources. What are they?

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(b) Fungi can decompose organic matter because they produce substances that break it down.

What are these substances called?

3. Match the method of mould ripening to the mould application of cheese. (a) surface ripening

•

•

from the inside out

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I C .P bl i at i ons • R •. from the u outside inc What is the difference between the products of respiration and fermentation of sugar •f orr evi ew pur posesonl y• by yeast?

(b) mould injection

4. (a)

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Use the text on page 7 to complete the following.

(b) What is the difference between the conditions in which respiration and

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fermentation of sugar by yeast occur?

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5. In bread making, what causes: (a) the dough to rise? (b) the delicious smell?

6. In the production of soy sauce, what are the main roles of the added: (a) mould?

(b) yeast?

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Foul fungi Biological sciences

Fungi can be found everywhere but what are their favourite growing conditions? Your challenge is to investigate the optimum conditions for fungal growth.

You should choose foods which you think will be easily broken down, then decide on the different conditions in which to leave them.

What foods will you choose and why?

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Where will you leave the samples and why?

What do you expect to discover?

How will you ensure a fair test?

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How often will you observe the samples?

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How will you record your observations?

For how long will you conduct the investigation?

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What did you discover?

Did it match with your prediction?

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What can you conclude from your investigation?

Would you alter anything about the investigation?

How will you communicate the results of your investigation.

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Why do plants and animals need to adapt?

Inquiry skills focus:

The lessons

Plant and animal adaptations to the environment

• Pages 11 and 12 should be used together.

• Explain the meaning of ‘adapting to the environment’. How do we adapt to ours? For example: − behavioural: warmer clothing in winter, sun protection in summer, walking to and from school with a friend for safety − body parts: skin covered in fine hair to trap air, giving us a layer of insulation when it’s cold.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• Explain that biodiversity is the variety of life (plants, animals and microorganisms) in a given biome or ecosystem.

• Create lists of different plant and animal adaptations suggested by the students.

• Plants and animals need to adapt to their environment so they can survive, reproduce and flourish. Failure to adapt spells doom for the species.

• Study the completed table so that students understand the task on page 13.

• An adaptation is a change in behaviour or body part that helps an animal survive in its environment. Examples of modified animal behaviour include hunting prey in packs, and roaming in large groups for protection against predators and for migration.

Answers Page 12

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1. adapted 2. (a) waxy coating on leaves or needles, losing leaves in autumn (b) fire-resistant bark and roots (c) growing close to the ground and in clumps, covered in hair, thick bark 3. circular flowers to track the sun; dark, brightly coloured or wide leaves to absorb more sunlight; climbing other plants to reach the sunlight 4. (a) fertile soil, plenty of rain, warmth (b) more fertile soil and better growing conditions 5. Grasslands are more windy as grassland plants have adapted to wind pollination and surviving fire. Tropical rainforests are densely covered with plants and have an abundance of insects for pollination.

This would not be the case if it was very windy.

6. Possible answers (a) Bactrian camel nose, eye and hair-lined ears for protection against blowing sand; growing an outer waterproof top coat and a thick, warm undercoat in winter; front legs and paws for digging (b) Parrots have tough beaks for cracking nut shells; sea otters have sensitive whiskers to detect fish. (c) Polar bears have wide paws for walking on snow; a pondskater’s legs allow it to move more easily on water; migration, hibernation or surviving on stores collected during autumn.

7. Large predators and harsh weather Science as a Human Endeavour question Nature and development of science Teacher check

• Examples of modified animal body parts include: teeth suited to method of eating, ability to see at night, protection against predators such as armour (armadillo) or spines (echidna).

• Examples of plant adaptations include methods of dispersing seed, brightly coloured flowers to attract pollinating insects, and tasty fruit to attract foraging animals that will disperse the seeds in their droppings.

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• Useful websites: − <http://www.woodlands-junior.kent.sch.uk/Homework/ adaptation.htm> − <http://www.idahoee.org/adaptations.htm> − <http://www.mbgnet.net/bioplants/adapt.html>

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Content focus:

Preparation

• Collect posters, photographs and illustrated books about plants and animals in different biomes.

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• Research one plant and one animal as a class or in small groups, completing the table on page 13 as an example page.

Page 13 Teacher check

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A biome is a community of plants and animals that has adapted to its climate and soil conditions. Earth has six major land biomes and two water biomes that are located at varying latitudes across the globe (from polar to tropical regions). Many species are very adaptable and can be found in more than one biome but others are unique to just one.

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Why do plants and animals need to adapt? – 1

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Climate, soil conditions and altitude of a biome determine the plants that can grow there and the food web it can support. Fertile soil combined with lots of rain and heat produces rich vegetation that can sustain a food web teeming with many animal species, as in tropical rainforests.

Poor soil that is low in nutrients, combined with harsh weather conditions, yields low biodiversity, as in tundra.

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• store water in leaves or stems • have waxy leaf coating to reduce water loss • flowers open at night to attract nocturnal pollinators

Plant adaptations

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• are evergreen and can make food as soon as it’s warm enough

• grow on or climb other plants to reach sunlight • have specialised roots to hold plants in shallow soil • brightly coloured flowers to attract pollinators

• produce seeds that float • have leaves that float to absorb more sunlight • have air sacs in stems to hold plant upright in water

Tropical rainforest

Water

• lose leaves in autumn to reduce water loss

Deciduous • have wide leaves to absorb more sunlight forest

• have thick bark to protect against winter cold

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• are dark coloured to absorb more sunlight

Coniferous • have wax-coated needles to prevent moisture loss forest

Tundra

• grow in low-lying clumps to protect against wind and cold • have circular flowers that track the sun to keep the plant warm • are covered with hair to protect against the cold

• have thick, fire-resistant bark Grassland • have fire-resistant roots to allow regrowth after a fire • are wind pollinated

Desert

Biome

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Biological sciences

The pond-skater’s legs allow it to move easily on water.

The sea otter has sensitive, long whiskers to detect the movement of fish.

Parrots have very tough beaks for cracking open nut shells.

In the cold winters, animals either migrate, hibernate or survive on stores collected during the autumn.

Many animals grow a thick fur undercoat and a waterproof hairy top coat to protect against the cold and wet of winter.

The arctic fox and hare change the colour of their coats: white for winter, brown for summer.

The polar bear has wide paws for walking on snow.

The front legs and paws of some grassland animals are good for burrowing into the ground to provide shelter and protection.

The Bactrian camel has nostrils that can close shut, long eyelashes and hair-lined ears to protect against blowing desert sand.

Animal adaptations

For their survival, plants and animals have had to develop different ways of adapting to their environments; for example:

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Why do plants and animals need to adapt? – 2 1. Plants and animals in a biome have

to

the climate and soil conditions of a region.

2. How do some plants protect themselves against: (a) water loss? (b) fire? (c) cold and wind?

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3. How do some plants make the most of the sun’s energy?

4. (a) What three things are required for abundant plant growth? ,

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(b) Some biomes have greater biodiversity than others. Why do you think this is?

5.

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C.Publ i cat i ons How do you think the wind conditions in the grassland and tropical rainforest biomes compare? Give reasons your answer.

•f orfor r e vi ew pur posesonl y•

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6. Give two examples of each type of animal adaptation. (a) Physical adaptations for protection:

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Use the text on page 11 to complete the following.

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(b) Physical adaptations for feeding:

(c) Behavioural adaptations:

7. Many grassland animals live underground. What would this type of home protect them from?

By studying the planet’s biodiversity, scientists discovered that life on Earth developed slowly as species adapted to changing conditions. Choose a plant or animal and investigate how its adaptations have evolved over time.

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Plant and animal adaptations Biological sciences

Choose a plant and an animal from different biomes and research how they have adapted to their environments.

Plant Name Biome description

Physical adaptations

How adaptations aid survival

Name

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(illustrate)

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Biome description

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Behavioural adaptations

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Body part adaptations (illustrate)

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Food

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How adaptations aid survival

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AUSTRALIAN CURRICULUM SCIENCE

Why do animals migrate or hibernate?

Inquiry skills focus:

The lessons

Physical conditions that result in animals migrating and hibernating

• Pages 15 and 16 should be used together.

• After completing pages 15 and 16, the following activity can be done. Make an explosion chart of animals that hibernate and those that migrate. Compare and contrast animals on each chart.

Discuss reasons why animals need to migrate: to find food, warmth and shelter as they escape the coming winter; returning home to breed and rear young in the spring/summer. Discuss the different types of hibernation; for example, hedgehogs and tortoises that go into a deep sleep and do not rouse until the spring. Many species of squirrel hibernate until the spring but some remain active, spending most of the winter in their nests and only coming out if there is a warm spell and they can replenish their stocks.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• True hibernation involves a state of inactivity and metabolic depression in animals, characterised by lower body temperature, slower breathing and lower metabolic rate. An animal in true hibernation appears dead and is insensible to sound or touch. There is no movement and it takes a long time for the animal to wake up enough to move. Some true hibernators include bats, rodents, ground squirrels, marmots, woodchucks, dormice, hamsters and hedgehogs.

• Discuss the answers the students provide for Question 8 on page 16 and relate these to page 15.

Answers Page 16

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1. food, water, shelter, rearing young 2. During hibernation, an animal’s body conserves energy by reducing its metabolism, body temperature and breathing rate.

3. (a) The purposeful movement from a place of reduced food, water and shelter to one of abundant food, water and shelter. (b) The animals detect natural changes in their environment; for example, less daylight hours and an abundance of autumn food.

4. (a) Plants begin to shut down by dispersing their seeds, shedding their leaves and preparing themselves to survive the winter. (b) Herbivores have a reduced supply of food and may migrate or hibernate, reducing the food supply for carnivores.

5. They eat enough food to produce layers of fat that will nourish them through the winter.

6. Breeding grounds are areas where animals know there will be plenty of food to feed themselves and their young as well as providing shelter to protect them.

7. the drying up of watering holes and pastures caused by lack of rain 8. hours of daylight, plants and animals visible including young, weather conditions (snow, ice etc), leaves on trees (or none), water resources available etc.

• Some hibernating animals (for example, bears) are not true hibernators. Their body temperatures do drop below normal and while they do sleep in their dens, they can be woken by a rise in outside temperature or a great disturbance.

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• True migration is seasonal and includes an outward and an inward journey. It generally occurs as a response to the basic needs of food, shelter and weather. Animals that are non-migratory are referred to as resident or sedentary.

• Useful websites: − <http://www.backyardnature.net/birdmgrt.htm> − <http://news.nationalgeographic.com/news/2001/10/1012_ TVanimalnavigation.html>

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Content focus:

Preparation

• A map of the world with labelled migratory routes of some well-known animals would be useful. Classify those who migrate to a specific breeding place and those who return ‘home’ to breed in the spring/early summer.

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Teacher check

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Why do animals migrate or hibernate? – 1 Biological sciences

What is migration?

r o e t s Bo r e p ok u S What is hibernation?

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Migration is the purposeful movement of animals from one place to another. It may occur seasonally, just once in a lifetime or whenever the environment dictates that it is time to move on. Although many species of animal migrate, birds are the best known travellers, with some, such as the arctic tern, flying across the globe in search of warmer conditions.

Seasonal migrating animals begin to move when they detect natural changes in the environment; for example, less hours of daylight and an abundance of food as nature’s autumn harvest ripens. They prepare for their long journey by eating well and producing layers of fat that will maintain them until they reach their next stop.

Hibernation is a winter sleep—nature’s way for animals to conserve energy when environmental conditions are too harsh for survival.

The animal’s metabolism drops to very low levels, gradually using up the fat stored during the autumn when food was abundant.

Energy is also conserved as the body temperature and breathing rate fall. Some animals hibernate very deeply; for example, the European hedgehog does not wake up at all until the spring. Others may stir regularly; for example, some species of bear.

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C. Pwater uband l i c at i orearing nsyoung are the driving food, shelter and forces of an animal in the wild. When the environmental conditions •f orr ev i ew ur p oors eson y•survival make any ofp these diffi cult impossible, anl animal’s instinct informs it that something has to be done.

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In many parts of the world, winter is a lean time. Temperatures can fall below freezing and snow and ice cover the land, making the search for food almost impossible.

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With the onset of autumn, many changes occur in the natural environment. The days shorten and the temperature falls. Plants are unable to photosynthesise effectively and so they begin to shut down, dispersing their seeds, shedding their leaves and preparing themselves to survive the winter. In this state, they provide no nutrition to animals that feed off them. This has an effect on all consumers—carnivores as well as herbivores.

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An animal’s instinct is to provide food for its young to give them the best chance of survival. Many animals instinctively migrate to a place with an abundant source of food where they can breed and rear their young.

For example, in the Serengeti in September each year, thousands of grazing animals (such as wildebeest, zebras, elephants and gazelles) migrate in search of watering holes and lush pastures. When the water and grass disappear, the animals move to the next stage on the route where the rains have fallen and provided new watering holes and fresh, young grass.

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Why do animals migrate or hibernate? – 2 1. What are the four necessities that motivate a wild animal?

2. Describe how an animal’s body behaves during hibernation?

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3. (a) What is migration?

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(b) How do animals know when to migrate?

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4. (a) What do plants do in response to reduced hours of daylight and lower temperatures?

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(b) How does this affect herbivorous and carnivorous animals?

5. How do animals prepare for migration and hibernation?

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6. Why do some animals migrate to breeding grounds?

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Use the text on page 15 to complete the following.

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7. Describe what motivates migration in the Serengeti.

8. If you were living in the wild with no communication with the rest of the world, what natural clues could you use to inform you of the time of year?

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Wild animals are faced with either migration, hibernation or adaptation at some point in their lives.

Their reasons are motivated by a natural urge to find food, water and shelter and/or to breed.

Research the nature of migration and hibernation by studying one animal that goes through each process.

Migration Animal species/subspecies

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Natural habitat/location

Main food source

Where it migrates to, when and why

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Hibernation

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Animal species/subspecies

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Main food source

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Where it hibernates, when and why

Interesting facts

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Biological sciences

Migration and hibernation

What happens when materials are mixed?

Content focus: Inquiry skills focus:

− siphon: to transfer using a siphon (an enclosed tube or similar through which a liquid is conveyed from a container at one elevation to a lower elevation). The liquid is forced into the tube by suction or immersion and then, once the tube is raised with a short section to the higher end and a long section to the lower end, the liquid falls (due to gravity), creating suction at the higher end which draws liquid through the tube.

Possible outcomes when materials are mixed Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• For the activity on page 21, the students should use colanders and sieves of different sizes and types; for example: absorbent paper and coffee filters, a range of plastic and acrylic containers and funnels.

r o e t s Bo r e p ok u S The lessons

Background information

• Pages 19 and 20 should be used together.

• Most reversible changes are physical changes.

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• For the test on page 21, dirty the water using a range of nonhazardous materials. For the test to be fair, each group must be given an equal volume of the test water after it has been stirred thoroughly.

Compare filtered samples by collecting in clear acrylic glasses and observing them against a plain white backing. This will highlight any debris remaining in the water.

• Reversible changes made by mixing materials can be reversed by filtration (of insoluble materials), evaporation (of soluble materials), sieving (materials of different sizes) and pouring (liquids of different densities).

• Some actions create an irreversible physical change; for example, beating an egg alters the consistency of the egg irreversibly but the chemical composition of the egg is the same.

Answers

• Useful websites: − <www.scittscience.co.uk/2009/01/ materials-revision/> − <http://www.sciencekids.co.nz/gamesactivities/ reversiblechanges.html> − <http://www.collaborativelearning.org/reversiblechange.pdf> − <http://www.bbc.co.uk/schools/scienceclips/ages/10_11/ rev_irrev_changes.shtml>

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1. Across: 1. soluble 4. reversible 9. distillation 10. miscible 11. separation Down: 1. sieving 2. filtration 3. reaction 5. evaporation 6. density 7. particles 8. siphoning 2. Step 1: Filter the talcum powder from the water.

Step 2: Evaporate the water from the solution to leave the salt crystals.

3. In a reversible change, there is no chemical reaction between the materials and no new substance is formed. The materials can return to their original state. In an irreversible reaction, a new substance is formed, which is evidence that a chemical reaction has taken place.

The materials can not return to their original state.

4. Sand and sugar can be separated because the particles of sugar dissolve in water, which can be filtered to remove sand and soluble sugar can be retrieved by evaporation.

Preparation

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• After the students have read page 19, explain the concepts and ensure they understand all the terms included. (See Preparation.)

• Materials can be changed by mixing with another material, heating, cooling and burning.

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• The students will need some knowledge of the following terms: − evaporation: the process of converting a substance into a gaseous state or vapour − filtration: the process of passing a liquid through a filter (a device made from cloth, paper, porous porcelain, or a layer of charcoal or sand) to recover solids − miscible: capable of being mixed − immiscible: incapable of being mixed − particle: a minute portion, piece or amount − solvent: the substance in which a solute dissolves − solute: the substance that dissolves in a solvent − solution: the mixture of a solvent and a solute − soluble: describes a solid that will dissolve − insoluble: a solid that will not dissolve − solubility: the degree by which a solute will dissolve in a given volume of the solvent at a given temperature

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Students should investigate websites such as <http://www.youtube.com/ watch?v=Q0s71cjCNWs> and view images such as <http://www.soninternational.org/images/filter.jpg> before commencing their design.

The students should consider the methods of separating liquid–solid mixes such as those on page 19.

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What happens when materials are mixed? – 1 When different materials are mixed together a number of things may happen.

Example 1: The liquids do not mix. They are immiscible. The more dense liquid sinks to the bottom and the less dense rises to the top.

Example 1: The solid does not dissolve. It is insoluble in the liquid.

Example 1: If the solids have different-sized particles, they can be separated by sieving.

There is no chemical reaction between the two. The solid can be separated by filtration.

Examples:

Examples:

flour and instant coffee grains Flou r

vinegar and sawdust

olive oil and water

Example 2: The liquids do mix because they have equal density. They are miscible.

Example 2: The solid dissolves. It is soluble in the liquid.

They do not react with each other. This is a reversible change. They can be separated by distillation.

There is a chemical reaction between the two, resulting in a new substance being formed. The change is irreversible. The solid can not be separated from the liquid.

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Solid–solid mix

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They do not react with each other. The two liquids can be separated by siphoning.

Examples:

Liquid–solid mix

Example 2: The solids have same-sized particles and one dissolves in a liquid but the other does not. They can be separated by adding the liquid, filtering the insoluble solid and separating the soluble solid by evaporation.

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C.Publ i cat i ons The liquids are heated until •f o rofr e i ew pur posesonl y• the lower boiling point thev Examples: Examples: vinegar and baking soda

Examples:

Baking

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soda

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Example 3: The liquids do mix because they have equal density. They are miscible.

Example 3: The solid dissolves. It is soluble in the liquid.

The liquids react with each other to form another substance.

This is an irreversible change because the liquids can not be separated.

There is no chemical reaction between the two. The change is reversible. The solid can be separated by evaporation.

Examples:

Examples:

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Example 3: The solids have same-sized particles and both dissolve in all liquids. They can not be separated easily.

Examples:

salt and caster sugar

CASTer

SUGAR

water and salt Acid

acid and alcohol

sand and sugar using water

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two liquids is reached. This vapour is then collected in a condenser, where it returns to its liquid phase.

CH3OH

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Chemical sciences

Liquid–liquid mix

What happens when materials are mixed? – 2 Use the text on page 19 to complete the following.

1. Write the words to complete the puzzle.

Down 1. A way of separating two solids of different sized particles.

2. A way of separating a solid from a liquid in which it is insoluble.

3. This can occur between two substances.

Across 1. Solids that dissolve in a liquid are this.

4. A change that can be returned back to its original state.

9. A way of separating two liquids.

10. Liquids that mix together are this.

1.

11. Splitting up.

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3.

5.

4.

6.

7.

8.

5. A way of separating a solid from a liquid in which it is soluble.

6. The mass of a substance in a given volume.

7. Small pieces of a solid.

8. A way of separating two immiscible liquids.

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10.

11.

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2.

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2. Explain the steps to separate a mixture of table salt and talcum powder.

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3. What is the difference between a reversible and an irreversible change?

4. Explain why sand and sugar can be separated.

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Clean dirty water Clean water is essential for everyone, yet for many people in the world their water supply is contaminated and needs to be purified in order to be safe to use.

In groups, your task is to use a selection of simple kitchen equipment and household materials to design the best filtration system for cleaning dirty water.

Before you begin

r o e t s Bo r e p ok u S Designing your system

Draw and label a sketch of your design, explaining how it works.

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How will you compare the filtered samples? Is this a fair comparison?

Evaluate your design

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Did water pass easily through the system?

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What parts of the design worked well?

What parts of the design need improving?

Evaluating all designs What feature contributed to the most successful design?

What feature contributed to the least successful design?

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Chemical sciences

How will you ensure a fair challenge for each filtration system?

What is solubility?

Content focus: Inquiry skills focus:

Answers

Features of solubility

Page 24

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

1. (a) The solvent separates the solute particles and distributes them evenly throughout the water. The solvent dissolves the solute particles from the surface layer inwards, until all particles have been dissolved. (b) Increasing the surface area of the solute by crushing it into smaller particles; stirring the solute as it is added to the solvent 2. (a) The mixture of a solute and a solvent (b) The solid that is dissolved by the solvent (c) The substance that dissolves the solute (d) The greatest amount of solute that can be dissolved in a known quantity of solvent at a given temperature (e) The point at which no more solute can be dissolved (f) A solution containing the maximum amount of solute 3. (a) high solubility (b) low solubility 4. by raising the temperature of the solution 5. (a) The solution would no longer look clear. (b) The solute would not dissolve and could be seen as the solution becomes very cloudy and solute could be seen at the bottom of the glass.

6. Because it can dissolve so many different solutes

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• Useful websites: − <http://www.ask.com/web?q=Fun+Experiments+with+Solubilit y&qsrc=6&o=10872&l=dir> − <http://www.blurtit.com/q381092.html> Preparation

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Students will discover that the solute in T1 takes longest to dissolve and that in T6 dissolves in the least time. The greater the surface area, the faster the dissolving time. If stirring is also incorporated, the time is reduced.

• Make an illustrated chart defining the words associated with solubility. Include familiar examples of solutes such as sugar and salt, and solvents such as water and oil.

• For the experiment on page 25, students will need sugar cubes, acrylic tumblers, marker pens for labelling, water at room temperature, measuring jugs, knives, stirrers and stopwatches.

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The lessons

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• In terms of liquids and solids, when a solvent (liquid) dissolves a solute (solid), the particles of the solvent separate the particles of the solute and then fill the spaces between. The molecules of some solutes and solvents are polar, meaning they have positive and negative electical charges. This allows attraction between the molecules and greater solubility.

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• The solubility of a solute is the maximum amount that can be dissolved in a given volume of solvent at a given temperature.

• Pages 23 and 24 should be used together.

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• The words associated with solubility are very similar and can be confusing. Discuss the meaning of each so that students are clear about which is which. Give examples, or find clues, to assist understanding and recall of definitions.

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• For the experiment on page 25, discuss how the test will be fair. The amount of solute must be the same for all tests so any stray sugar must be added to the tumbler it belongs with. Measuring the water must be done accurately. It is better to use a narrow jug than a wide one. The same person should stir the three stirred samples to ensure consistency of force. Discuss the point at which the solute is seen to be completely dissolved: one moment it can still be seen, the next moment it can’t.

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What is solubility? – 1 When a substance dissolves in water, the powder or crystals are broken down into even smaller particles and distributed evenly throughout the water. This mixture of a solid dissolved in a liquid is called a solution. The solid is called the solute and the liquid is the solvent. The solvent separates the solute particles and takes up the space between the solute particles.

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solution

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(sugar) solute particles

saturated solution

The maximum amount of solute that can dissolve in a known quantity of solvent at a certain temperature is its solubility. Some things (for example, salt) are highly soluble in water because they dissolve easily. A solute that does not dissolve easily (for example, pepper) has low solubility.

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C.Publ i cat i ons A solute can be made to dissolve faster.

•f orr evi ew pur posesonl y• When a solute dissolves, it does so only on the outer surface of each particle. As the

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outside layer is dissolved, it exposes the next layer. This continues until the whole particle has disappeared. So a solute in a form with greater surface area will dissolve faster than those with lesser surface area; for example, a sugar cube dissolves more slowly than the same weight of sugar as loose crystals.

When a solute is stirred into a solvent, the stirring action brings the solute particles into contact with more solvent, thereby also increasing the dissolving rate.

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A liquid solvent can only dissolve a given amount of solute at a given temperature. If any more solute is added, the solution will no longer look clear. It will start to turn cloudy and the solute can be seen at the bottom of the container. When the solution stops looking clear, the solvent has reached its saturation point for that solute at that temperature and is called a saturated solution. There is no room in the solvent for any more solute molecules. But if the solution is heated, more solute can be dissolved until the saturation point for the solvent at the higher temperature is reached.

Not all solutes dissolve in all liquid solvents. Water is known as the ‘universal solvent’ because there are many solutes that will dissolve in it.

Solubility is an important factor in the manufacture of dehydrated foods. Instructions on the packets of dehydrated foods tell you how much water, stock or milk is required to make the product to the correct consistency. Such foods have made a significant contribution to the welfare of people living in areas where fresh foods are not readily available; for example, dried milk, which has all the nutrition of fresh milk, has been a life saver for young children living in famine struck areas of the world and where there have been natural disasters.

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(water) solvent particles

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(water) solvent particles

What is solubility? – 2 Use the text on page 23 to complete the following.

1. (a) What happens to the solute as it is added to a solvent and dissolves?

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2. Write the definition for each word or phrase.

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(a) solution (b) solute

(c) solvent

(d) solubility

(e) (f)

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C.Publ i cat i ons saturation point •f orr evi ew pur posesonl y• saturated solution

3. Match the correct pairs •

•

low solubility

(b) does not dissolve easily •

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high solubility

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(a) dissolves easily

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4. How can a saturated solution be made to dissolve more solute?

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(b) Write two ways a solute can be made to dissolve faster.

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5. (a) How could you tell that a solution was reaching its saturation point?

(b) What would happen if more solute is added to a solution after the saturation point is reached?

6. Why is water called the ‘universal solvent’?

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The effect of particle size and stirring on solubility How long does it take for a solute to dissolve in a solvent?

The answer to this question depends on the surface area of the solute particles and how much, if any, stirring takes place.

You will conduct an experiment to determine how particle size and stirring affect the time it takes for sugar to dissolve in water that is at room temperature.

Prediction:

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• 24 cubes of sugar • water at room temperature

• 6 acrylic tumblers labelled from T1 to T6 • stirrer • measuring jug

• knife

What to do:

Prepare the solute.

• stopwatch

Add the solute to the solvent.

• Leave 8 sugar cubes for T1 and T2, whole (4 for each).

(a) Add the 4 whole sugar cubes to T1 and at the same time, start the stopwatch.

Record the time it takes for all the sugar to dissolve.

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C.Publ i cat i ons •f orr evi ew pur posesonl y• (b) Add the 4 whole sugar cubes to T2 and at • Cut the sugar cubes for T5 and • Cut the sugar cubes for T3 and T4 in half (8 halves for each).

the same time, start the stopwatch. Stir the solute for 5 seconds after adding the cubes. Record the time it takes for all the sugar to dissolve.

T6 into quarters (16 quarters for each).

Results:

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Add 200 mL of water to all tumblers.

Repeat steps (a) and (b) for T3 and T4, and then for T5 and T6.

Record all times in the table.

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Whole cubes

Halved cubes

Quartered cubes

Without stirring

With stirring

Without stirring

With stirring

Without stirring

With stirring

T1

T2

T3

T4

T5

T6

Conclusion: What can you conclude from this experiment?

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You will need:

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What do you think will be the outcome of this experiment?

What changes do heating and cooling cause?

Content focus:

Inquiry skills focus:

The lessons

How temperature changes affect the molecular structure and bonding of a substance and how this alters the state of the substance

• Pages 27 and 28 should be used together.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Teac he r

Background information

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• Heating and cooling can cause changes to substances, some reversible, some irreversible.

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• Almost all substances have freezing, melting and boiling points. If a substance is not a mixture or not contaminated in any way, these temperatures can be used to identify or confirm the identity of a pure substance.

• For the investigation on page 29, students should make up about six salt water solutions of known concentration; for example: 2.5%, 5%, 7.5%, 10%, 20% and 50%. As a control, they will need a plain water sample. All weighing must be carried out on the same scales and water measured using the same apparatus. When the solutions are made, they will be placed in a domestic freezer and examined at set intervals of time for ice formation. At this point, the temperature of the sample is taken. Students should initially record their results in a table and then graphically showing, salt concentration vs freezing temperature. Students may need to be reminded what a control and a fair test are (refer to pages 2 and 6).

• Heating and cooling a substance changes its state from liquid to solid to gas (and vice versa if the change is reversible). This is related to how tightly the molecules of the substance are held together.

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• Useful websites: − <www.scittscience.co.uk/2009/01/ materials-revision/> − <http://www.sciencekids.co.nz/gamesactivities/ reversiblechanges.html> − <http://www.collaborativelearning.org/reversiblechange.pdf> − <http://www.bbc.co.uk/schools/ks2bitesize/science/materials/ reversible_irreversible_changes/read1.shtml>

Answers Page 28

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Preparation

1.

2.

3.

4.

(a) false (b) true (c) false (d) true (a) boiling point (b) molecules (a) liquid (b) gas (c) solid (a) When a liquid is heated above boiling point (b) When a gas is cooled below boiling point.

5. The heat energy is used to break the bonds holding the liquid molecules together and instead forms a gas.

6. They must be collected and cooled.

Science as a Human Endeavour questions Nature and development of science Teacher check Students can research the freezing, melting and boiling points of substances such as water, milk, sunflower oil etc.

• For the activity on page 29, provide water, table salt, spoons, weighing scales, containers, measuring jugs and stirrers for making up the solutions. Also provide thermometers capable of measuring low temperatures and access to a domestic freezer.

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• Take time to explain the concept of the bonding of atoms within molecules, and bonding in the solid, liquid and gas phases. This can be done in an open space with each child playing the part of a molecule. In a solid, the molecules are held together in a rigid structure. Group the students into rows and columns. They place the left hand on the shoulder of the person in front of them and put the right arm around the person to their right. Their arms are the bonds holding the molecules together. In the column to the right and the row at the front, each molecule has an unused bond, this is for attaching to more molecules. In a liquid, the bonds are still present but as it is heated, the molecules start to move and loosen the bonds.

To show this, students jog on the spot and loosen their right arm bonds. In doing so they move further apart. They are starting to melt!

In a gas, the bonds are broken completely and the molecules are free to take up the whole space available to them. Students drop both arms and move around the whole area. Only if they are contained in a small area can they be cooled and condensed.

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Teacher check. Students should find that the more salt is added, the lower the freezing point.

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What changes do heating and cooling cause? – 1 Atoms are the building blocks of everything.

Most things are made up of two or more types of atom. They are joined together as molecules by forces of attraction called bonds. A well-known example of a molecule is water, which is made of two atoms of hydrogen bonded with one atom of oxygen.

As a solid substance continues to melt, its temperature does not rise even though it is still being heated. The heat energy is being used to speed up the molecules of the solid until the substance is all liquid (at which point its temperature will start to increase). That is why snow, even as it is melting, is always cold.

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O H

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A water molecule

When a liquid substance is heated, the temperature at which it starts to boil is called its boiling point. The bonds between the molecules are broken and the liquid evaporates as the molecules disperse as a gas.

When a substance is heated and cooled, it changes between the states of solid, liquid and gas. In a solid, the molecules, held together as a rigid structure. As the substance is warmed, the molecules begin to move and separate from each other as the bonds among them weaken. This is what happens as a solid melts. The more heat that is applied, the faster the molecules move.

When a substance is cooled, the reverse happens. The molecules slow down and move closer together, until they form their rigid structure again.

The gas can be collected in a condenser and cooled to a liquid again. If it is not collected, the gas spreads into the atmosphere.

Temperature

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MP

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ate

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Solid starts to melt.

Solid

Liq

Liquid starts to evaporate.

Liquid is completely evaporated.

MP – Melting point

Solid is completely melted.

BP – Boiling point

Time

The water cycle is an example of the constant change of state of a substance. Water is constantly moving among its three states of matter. In oceans, lakes, swimming pools and puddles, water evaporates into water vapour (gas), which later condenses and falls as rain, hail or snow. When the temperature falls to 0 °C and below, ice forms.

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When a solid substance is heated, the temperature at which it starts to melt is called its melting point. This is the same temperature at which the substance in its liquid form starts to freeze when it is cooled. The melting and freezing points of a substance are the same.

What changes do heating and cooling cause? – 2 Use the text on page 27 to answer the questions.

1. Answer as true or false. (a) The molecules in a solid move very quickly. (b) When a liquid is cooled, its molecules slow down. (c) The molecules of a gas are tightly held together.

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(d) The freezing and melting temperatures of a substance are the same.

2. Read the clues to find the answers to the riddles.

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I am a b

p

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(a) I am a reading on a thermometer. When I am reached, the molecules of a substance move very fast and break apart from each other as the bonds among them are broken.

The substance begins to evaporate. What am I? .

(b) We are groups of atoms held together by attractive forces. In a solid, we are stationary and held as a rigid structure. In a liquid, we can move a little and are held together more loosely. In a gas, we are completely free unless we are captured in a condenser and cooled down. What are we? . u © R. I .

C.P bl i cat i ons In which state or phase (solid, liquid or gas) is a substance in if its temperature is: •f orr evi ew pur posesonl y• We are m

3.

(a) between melting point and boiling point?

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(b) above boiling point?

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(c) below freezing point?

4. (a) When does evaporation occur?

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(b) When does condensation occur?

5. When a liquid is heated to its boiling point and continues to be heated, the liquid does not get any hotter. Why not?

6. For condensation to occur, what must happen to the escaping gas molecules?

The freezing, melting and boiling points of various substances can help scientists identify unknown substances. Find out these values for a number of familiar substances. Plot them on a graph to compare them.

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Just add salt!

In places that experience cold winters, when icy roads create hazardous driving conditions, some local councils spread salt on the roads to reduce the freezing point of the water on the roads’ surface. This reduces the temperature at which it turns to ice. This can reduce the freezing point of the water to far below 0 °C. Your task is to find out how much the freezing point of water is reduced when known amounts of salt are added to the liquid.

Complete the table by answering the questions.

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How much salt will you add to each salt water solution?

What will you use as the control?

How will you ensure a fair test?

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What do you expect the outcome of the investigation to be?

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How will you carry out the test?

What equipment will you need?

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How will you record your results?

How will you present your results?

After your investigation How did your results compare to your prediction?

What changes would you make to improve your investigation?

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How many salt water test solutions will you make?

Why do metals rust?

Content focus: Inquiry skills focus:

• For the activity on page 33, the students need to accurately prepare a number of salt solutions of different concentrations, add a nail (or similar metal object) to each solution and observe what happens over time. They need to draw up a table to record their observations for each solution sample. To ensure a fair test, all metal objects should come from the same source and be free of rust. They must be non-galvanised. The water must come from the same tap and be of the same temperature. The salt must come from the same packet.

Students record what they expect to see and then exactly what they do see. Discuss their observations, allowing them to derive an explanation.

Conditions and chemical reactions that cause rusting Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

Answers

Teac he r

• When iron corrodes, rust is formed and the iron loses its metallic properties; i.e. electrical conductivity, strength and shine. The process, which occurs through oxidation (combination with oxygen), produces iron oxide (rust).

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1. rust 2. (a) air and water (b) Teacher check. Students should include the components: metal, air, water and rust 3. When salt water evaporates from metal, it leaves salt behind. The presence of salt speeds up the rusting process.

4. (a) Acid dissolves metal. (b) Acid dissolves rust before it attacks metal.

5. (a) A metal that combines easily with other elements/react more readily/corrode easily. (b) the more reactive metal 6. Humid; there is a lot of moisture in the air, which continues the rusting process.

Science as a Human Endeavour question Nature and development of science Teacher check Visit the website <http://nobelprize.org/nobel_prizes/lists/all/> to find a list of Nobel Prize winners.

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• Rusting is an example of corrosion, which is an electrochemical process in which electrons given up by the iron combine with oxygen in the presence of water and accumulate as rust.

• Steel is used commonly in the construction of buildings and other large structures, as well as household items. It is an alloy of iron, and is iron with carbon added to increase strength. It also increases iron’s ability to resist oxidation, and does not rust as easily as wrought iron.

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• Non-reactive metals, such as gold, are resistant to oxidation. They are called noble metals. They occur naturally although they are rare.

• Reactive metals such as iron are mined in their ore states. A metal ore, found in rock, contains traces of the metal. The ore is extracted by mining and then refined to obtain the metal.

• Dynamite, which is used extensively in the mining, quarrying and construction industries, was invented by Alfred Noble.

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• Useful websites: − <http://www.haverford.edu/educ/knight-booklet/mustitrust. htm> − <http://www.kids-science-experiments.com/shinycoins.html> Preparation

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• Students will need to make up a number of salt solutions of increasing and known concentration.

• They will also require a plain water control.

• For a fair test, the metal they use must be the same for each solution; e.g. iron nails from the same packet.

• At set times, they will have to record exactly what they see happening in each solution. These observations are best recorded in a table.

• Students will observe that rusting occurs more rapidly in the strongest salt solution. The chemical reaction that takes place on the surface of the metal involves electron transfer which occurs more rapidly in salt water because salt water is a better conductor of electricity than plain water.

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• Make a collection (or find pictures) of rusting objects for students to view and discuss.

• For page 33, provide sufficient nails, plastic cups, salt, stirrers, measuring jugs and weighing scales for each student or group of students.

The lessons • Pages 31 and 32 should be used together.

• After examining the rusting object, note how corrosion eats at the metal. Discuss the implications of this for safety and longevity of metal objects. Discuss what students already know about protecting metals from corrosion.

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Why do metals rust? – 1 metal + air + water = rust If a steel bicycle is left out in the rain, orange-red marks will soon appear on the chain, sprockets, handlebars and other places where the metal is unpainted. This is rust. If nothing is done to stop it, the rust will continue to corrode the metal.

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Water is the main cause of rusting. When it comes into contact with an unprotected metal, two reactions begin. Hydrogen in the water combines with carbon dioxide in the atmosphere and forms a weak acid. As the acid begins to dissolve the metal, oxygen in the water combines with the dissolving metal and iron oxide (rust) is formed. This corrosion cycle will continue for as long as the metal is in contact with water or even if the air is heavy with moisture, like it is on a hot and humid day.

Scientists have discovered that some metals react with water and oxygen more readily than others. Reactive metals corrode easily. Through scientific discovery, a list ordering metals from the least reactive to the most reactive has been produced. This list has been valuable for scientific progress.

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C.Publ i cat i ons •f orr evi ew pur posesonl y• Cover the metal with oil or grease, which repel water; e.g. always oil your bike chain

How to prevent rusting

• Keep the metal dry or dry it thoroughly after it has been wet; e.g. keep your bicycle in the shed and always wipe it down if you have been cycling in the rain.

•

after you have cleaned it.

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• Paint the metal; e.g. the garden gate, outdoor metal furniture.

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• Use metal that has been galvanised—an industrial method for coating metals with a protective layer of a less corrosive metal; e.g. used in car manufacturing and ship building.

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• Use sacrificial protection; e.g. placing layers or blocks of more reactive metals next to or on ship hulls, oil rigs and underwater pipelines. The block or coating of metal rusts rather than the metal it is protecting. However, the sacrificial metal must be replaced before it is completely corroded.

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During the rusting process, at the same time as the acid is dissolving the metal it also dissolves the existing rust. Because of this, stronger acids are often used to clean rust because they will dissolve the rust before they attack the metal.

In some places, rust can be a significant problem because the presence of some chemicals in the environment adds to the rusting process; for example, where saltwater spray from the ocean reaches cars and buildings, or where acid rain is a problem. The salt and other chemicals which are dissolved in the water remain on the metal after the water evaporates, and can speed up the rusting process.

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Rusting is an irreversible change. Oxygen in the air and rain water have combined with the metal and created another substance, which is known as iron oxide.

Why do metals rust? – 2 Use the text on page 31 to complete the following.

1. Iron oxide is the chemical name for which common problem?

2. (a) What two elements are required for the rusting process to occur? and

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3. Rain causes metal to rust, but sea spray causes it to rust more quickly.

Explain why this is so.

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4. Explain how acid can: (a)

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(b) Draw a flow chart to explain how rust is formed.

5. (a) What is a reactive metal?

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(b) If pieces of two different metals were left together in a tray of water, which would rust first? Tick the correct answer. the more reactive metal

the less reactive metal

6. Rusting would be a greater problem in a

(dry/humid) climate because

Alfred Nobel was a famous scientist who discovered dynamite. For over 100 years, the Nobel Prize has been awarded each year to recognise scientific advances. Research some Nobel Prize winners and their contribution to scientific discovery.

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Rusting nails Does a stronger salt solution mean that rusting will occur more quickly?

Devise an investigation to answer the question.

What equipment will you need?

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What will you do?

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How will you ensure a fair test?

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C.Publ i cat i ons •record f orr evi ew pur posesonl y• How will you

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What I think will happen.

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What did happen?

Results/Observations

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your data?

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Explain what happened.

Further investigation How would you compare the rate at which the different metals corroded?

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Procedure

How is reversible change used in recycling?

Content focus:

Inquiry skills focus:

Answers

The reversible changes that allow recycling of glass, plastic and paper products

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Background information

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• There is no limit to how often glass can be recycled, provided it is not contaminated. To prevent contamination with other materials, only cleaned clear, green and brown bottles and jars should be recycled.

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• Glass is made from sand, silica and limestone. In the manufacture of most glass products, recycled glass, cullet, is added to these raw ingredients. The cullet lowers the overall melting point of the mixture and so less energy is required in the manufacturing process.

• Downstream recycling means that the recycled product (for example, plastic or paper) is of reduced quality compared to the original product from which it came. This means that, unlike glass, these materials can only be recycled a limited number of times.

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• Useful websites: − <http://www.benefits-of-recycling.com/ interestingfactsaboutrecycling.html> − <http://www.wastepaperrecycling.com.au/> − <http://www.industry-animated.org/extrusion.htm>

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1. (a) To reduce the impact on the environment caused by industrial paper making; for example: felling trees, and air and water pollution. Recycling paper uses less energy and also reduces landfill. (b) Most paper in everyday use—including newspapers, magazines, junk mail pamphlets, telephone directories, office waste and cardboard—can be recycled. (c) Pulping: Adding water and beating to separate fibres.

Screening: To remove contaminants greater in size than pulp fibres.

Centrifugal cleaning: Contaminants that are more dense than pulp fibres are thrown to the outside and separated as the pulp slurry is spun at high speed.

Flotation: Ink particles are attracted to chemicals added to the slurry. As air is passed through slurry, the chemicals foam and rise to the surface.

Kneading/Dispersion: Contaminants are reduced in size by beating.

Washing: Small particles of contaminant are rinsed away from the pulp.

Bleaching: Chemicals are added to brighten the paper if required.

Papermaking: The recycled fibre is used to make paper by the same process as pulp from bark.

Dissolved air flotation: The water used in the recycling process is cleaned and reused.

Waste disposal: The sludge remaining is buried, burned or used as fertiliser.

Preparation

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1. To reduce the amount of rubbish going into landfill; to conserve natural resources that are used to make new materials.

2. Recycling processes rely on the reversible change from solid to liquid and back to solid; the chemical properties of the materials allow them to be heated and cooled and yet remain unchanged.

3. Glass: waste glass collected; sorted into different colours; crushed into cullet; sand, limestone and soda ash added; heated to melting point; moulded into new bottles. Plastic: waste plastic collected; sorted into different grades; shredded into flakes; heated to melting point; formed into nurdles; sold in bulk.

4. Recycled glass is used to make the same products it came from; e.g. glass bottles. Recycled plastic is not used to make the same products it came from but is formed into nurdles and used in the manufacture of other products. Recycled glass requires the addition of other materials to the cullet.

5. To identify the grade of plastic used to make the item and for accurate sorting at the recycling centre.

6. Glass and plastic are heated to their melting points to become molten. Water is added to paper to return it to pulp. The paper pulp is cleaned a number of times.

Science as a Human Endeavour question Use and influence of sciences Teacher check

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

The lessons

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• Obtain/Draw large colourful flow charts of the recycling processes of glass, plastic and paper.

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• Pages 35 and 36 should be used together.

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• Collect examples of glass, plastic and paper waste. Discuss their differences and how they would be sorted at a recycling plant.

Discuss the reversible change element of the recycling process of each material.

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How is reversible change used in recycling? – 1 We all know how important it is to recycle as much material as we can. This helps to reduce the volume of rubbish going into landfill sites and to conserve natural resources that are used to make new materials.

Recycling glass and plastic is possible because the chemical properties of both materials allow them to be heated and cooled and yet remain unchanged. But unlike simply melting and refreezing an ice block, industrial recycling is more complicated.

NNEEWWS NNEEWWSS S

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There are many different grades of recyclable plastic, all of which are used for different products. For example, high-density polyethylene (DHPE) PETE HDPE V is used for plastic jugs and some toys, and low-density polyethylene (LDPE) is used for food wrapping and plastic 4 5 6 7 bags. Have you ever noticed the triangle formed with three LDPE PP PS OTHER arrows which is printed on plastic containers? It usually has a number between one and seven inside the triangle and letters outside it. This label identifies the type of plastic the item is made from and is used when plastics are sorted during the first stage of the recycling process.

3

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After it is separated into its different grades, the plastic is shredded into flakes. In this state, the material is heated to its melting point. The molten plastic is formed into pellets known as nurdles, which are sold in bulk and used in the manufacture of other products (for example, engineered woods like plywood and MDF).

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C.Publ i cat i ons f odoes rr ev i ew pu poses o nl y Recycling• plastic not reduce the need forr manufacturing new plastic but• it can reduce

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the demand for other resources; for example, less trees are felled to make wood products because engineered ‘wood’, which is stronger and more durable, is made using the plastic nurdles.

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With glass recycling, after it is collected the glass is sorted by colour (green, brown, clear etc.). After this the glass is crushed into small pieces and is then referred to as cullet.

Before the cullet is melted in a furnace, other raw materials used to make glass are added.

These include sand, limestone and soda ash. After being mixed at approximately 1500 °C, the glass can be moulded into new bottles and other products.

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Like glass, the paper making process is also reversible, allowing the tonnes of waste paper created every year to be used again.

Water and chemicals are added to the waste paper, which is then reduced to slurry in a pulper. The pulp goes through a number of cleaning processes before being made into paper again.

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Chemical sciences

2

Teac he r

1

How is reversible change used in recycling? – 2

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Use the text on page 35 to complete the following.

1. Give two reasons why recycling materials is important.

2. Why is it possible to recycle materials such as glass and plastics?

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3. Use the steps written below to create a chart for the recycling of glass and plastic. One step

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crushed into cullet formed into nurdles waste plastic collected moulded into new bottles sorted into different colours heated to melting point sand, limestone and soda ash added Glass

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sold in bulk shredded into flakes waste glass collected sorted into different grades Plastic

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4. What is the main difference between recycling glass and recycling plastic?

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Chemical sciences

is used for both materials.

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5. What is the purpose of the triangular label embossed on plastic items?

6. How do the recycling processes for glass and plastic differ from the paper recycling process?

Watch the animation at <http://www.industry-animated.org/extrusion.htm>, which shows how an extruder is used to make plastic piping. The melting and cooling of the plastic is an example of a reversible change.

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Recycling paper Recycling paper requires less energy than making new paper from bark.

The process is very effective and takes only a few days to complete.

The need for paper made from new pulp can be reduced by recycling all paper waste and buying paper products made from recycled paper.

Research information to complete the table. (a) Why should people recycle paper?

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(c) Explain with a sentence the ten steps of the paper recycling process.

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Pulping

Screening

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Centrifugal cleaning

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Flotation

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Kneading/ Dispersion

Washing

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Bleaching

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Papermaking

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Teac he r

(b) What types of paper can be recycled?

What causes a volcanic eruption?

Content focus: Inquiry skills focus:

The lessons

Causes and effects of a volcanic eruption

• Pages 39 and 40 should be used together.

• As an introduction, discuss famous volcanic eruptions (past and present) and locate them on a world map. Highlight the Pacific Ring of Fire.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• For the investigation on page 41, students will find that volcanoes can also be classified into five groups, including spatter cones and complex volcanoes.

r o e t s Bo r e p ok u S Answers

Background information

Page 40 1.

2.

3.

4.

inner core, outer core, mantle, crust The pressure pushing down on the inner core keeps the metal solid. molten (a) The large and smaller pieces of crust that cover the surface of the Earth. (b) The melted rock in the Earth’s mantle. (c) The joins between the Earth’s tectonic plates. (d) The melted rock (magma) that has been forced out of a volcano. (e) The hole at the top of a volcano through which lava explodes.

5. 1. eruption 2. pressure 3. chamber 4. crater 5. lava 6. mountain 7. lava 8. cools 6. (a) pyroclastic flow (b) tephra (c) lava 7. If a glacier on a volcano melts, it can turn the mud and debris from a collapsed volcano into a mudslide.

Science as a Human Endeavour question Nature and development of science Volcanologists use satellite imagery to study and track clouds of ash and gases ejected into the atmosphere by erupting volcanoes. They also study the changes in the shape of a volcano which may indicate impending activity. Heat from changes in temperature and lava (hot spots) can be detected by using thermal infrared sensors. They can study ground deformations, or detect and measure volcanic gases or the movement of lava underground.

• Volcanic eruptions can be classified as either: − effusive: Magma at 1200 ºC+ reaches the surface and because it is so hot, it flows easily, moving across the land. Gently-sloping shield volcanoes are produced in this way. − explosive: Dissolved gases can not escape easily from cooler, more viscous magma and so the pressure builds until the gas explodes, sending lava and rock skyward. As the lava flows more slowly, due to its more viscous consistency, a composite volcano with a steeper gradient is created.

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• Active volcanoes are dangerous neighbours to have for human, plant and animal communities, but they do produce fertile, mineral-rich soil, water reservoirs and geothermal resources as well as scenic beauty.

• Useful websites: − <http://library.thinkquest.org/17457/volcanoes/erupt.php> − <http://www.ga.gov.au/hazards/volcano/> − <http://www.kidsgeo.com/geology-for-kids/0037-the-earthearth-inside-out.php> − <http://www.amnh.org/ology/index.php?channel=earth>

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Preparation

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• Eruptions have also been classified as Hawaiian, Strombolian, Vulcanian, Peléan, Plinian, submarine and Surtseyan.

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Earth and space sciences

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• A cinder cone is a steep conical-shaped hill that forms next to a vent on the side of a composite or shield volcano. The cone consists of fragments of lava (called cinders) which have accumulated close to the vent from which they were released.

o c . che e r o t r s super Page 41

Teacher check The volcano erupts because the baking soda reacts with the vinegar, and carbon dioxide gas is released, causing the dishwashing liquid to froth and spill over the edge of the concealed plastic cup/bottle.

The results of the investigation will depend on the quantities of baking soda and vinegar used.

• Research to create a list of the most damaging volcanic eruptions in history. Record data such as location, amount of loss of life, extent of damage and further damage caused; e.g. landslides.

• Students will need to make their own model volcano construction to conduct the experiment on page 41. Refer to <http://crafts. kaboose.com/erupting-volcano.html>, <http://sciencebob.com/ experiments/volcano.php> or <http://www.activitytv.com/138erupting-volcano> for various options.

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What causes a volcanic eruption? – 1

r o e t s Bo r e p ok u S

© R. I .

C.Publ i cat i ons Once above ground, the magma is called lava. As it •f orr evi ew falls pu o sethe sground, onl •and hardens to r orp runs along ity cools

w ww pyroclastic flow

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crater

lava flow main vent

magma chamber

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and forms solid rock. Each time the magma erupts, the cooling lava creates a new layer of rock and the volcanic mountain increases in size. The hole at the top of the volcano is called a crater.

There are many elements associated with a volcanic eruption: The lava moves slowly, giving enough time for people to evacuate the area. It generally covers volcanic bombs a small area because it cools quickly, forming obsidian and pumice rock.

Falling ash and magma-formed rock (known as secondary cone tephra) can cover a wide area, having exploded violently from the volcano in a huge column.

Pyroclastic flows are a mixture of very hot gas and tephra. They can move very quickly down secondary vent the slopes of a volcano, giving little time for evacuation.

The mud and debris that belongs to a volcano Earth’s crust that has collapsed during an eruption can flow downhill with the lava and pyroclastic flow. If there is a glacier on top of the erupting volcano, the melting ice can turn the flow into a devastating mudslide.

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ash cloud

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Earth and space sciences

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crust Planet Earth is made of four layers: • The inner core is a solid ball of metal. Even though mantle it is incredibly hot (hot enough to melt metal), the pressure pushing down on it is so great that it remains solid.

• The outer core is a layer of molten metal that moves around the inner core. outer core • The mantle is the thickest layer. It is solid, but the inner core heat from the core causes it to move very slowly and this causes the movement of the Earth’s crust.

• The crust is the thin outer layer of the planet, and is (on average) about 35 kilometres deep. It is made up of eight large pieces and a number of smaller ones, and fits together like an irregular jigsaw. Each piece is called a tectonic plate.

The heat deep inside the mantle is so intense that solid rock can melt to form magma. This molten rock is hotter and lighter than the rock it came from and so it rises to the top of the mantle until it comes to rest in magma chambers a few kilometres below the Earth’s surface.

The chambers are located near fault lines in the Earth’s crust where tectonic plates meet. As a chamber fills with magma, the pressure in it builds. Sometimes the pressure is so great, it cracks the earth above it and seeps (or explodes) out of the Earth’s surface. These cracks act like valves to release the pressure, and the magma is released through large and small vents as a volcanic eruption of lava, rocks (bombs) and ash.

What causes a volcanic eruption? – 2 Use the text on page 39 to complete the following.

1. The four layers of the Earth are the: .

2. Why is the metal inner core solid even though its temperature is hot enough to melt metal?

r o e t s Bo r e p ok u S

3. What word in the text means the same as melted?

4. Write a definition for each. tectonic plates

(b)

magma

(c)

fault lines

(d)

lava

(e)

crater

5. Write the correct words to complete the text.

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Teac he r

(a)

occurs when the in a © R. I .

C.Publ i cat i ons magma becomes so great it is released like a valve. Magma is • f o r r e v i ew pur p osesonl y• released through the volcano’s in an eruption of 1

A volcanic

2

3

5

,

6

A volcanic

develops over centuries as flowing 8

from the active volcano

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to form layers of rock.

6. Write the correct word/phrase for each definition.

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rocks (bombs) and ash.

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4

7

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(a) A mixture of very hot gas, falling ash and magma rock (b) A huge column of ash and magma rock (c) Slow-moving magma above ground

7. How might a mudslide occur after a volcanic eruption?

Volcanologists observe the activity of volcanoes for information that might help them predict the timing and intensity of eruptions. Research to find out what facts they study.

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Create the most explosive volcano This experiment is in two parts. First you will follow a simple procedure in which two ingredients react to create a gas which causes the volcano to erupt.

You will then alter the proportions of the active ingredients and predict how these changes will affect the eruption.

You will need:

• a prepared volcano construction with a container

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hidden in the crater in which to mix the ingredients

• 1 tsp. dishwashing liquid • 30 mL vinegar • 2 drops each of red and yellow food colouring What to do:

• 2 tsp. baking soda

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Teac he r

Mix the first three ingredients, then add the baking soda and observe the reaction.

Results: Describe what you saw.

Conclusion: The volcano

because

.

Investigate the effect of changing the proportions of the active ingredients.

© R. I .

C.Publ i cat i ons •Baking f orr e vi ew pur pose sonl y• Vinegar Predictions

Trial

soda (tsp.)

Earth and space sciences

• Repeat the procedure using different proportions of each ingredient.

Remember to add the food colouring each time. (mL)

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1 2

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3

Trial 1 2

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3 Conclusion: because

The best proportion of ingredients was

.

How could the investigation be improved to create a better eruption?

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How are earthquakes and tsunamis related?

Content focus: Inquiry skills focus:

The lessons

Submarine earthquakes as the cause of tsunamis

• Pages 43 and 44 should be used together.

• Discuss recently occurring earthquakes and tsunamis. Highlight their locations on a world map, referring to any nearby fault lines between tectonic plates.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• Explain that the energy released by an earthquake is released as seismic waves which cause the displaced ground or water to move in waves of various sizes.

r o e t s Bo r e p ok u S Answers

Background information

Page 44

1. 1. movement/stability 2. land 3. sea 4. fault lines 5. crust 6. Earth 2. (a) Plates move apart from each other. (b) Plates push together. (c) Plates slide against one another.

3. (a) More damage at 1 km because the shock waves are stongest at the epicentre of the earthquake, which is immediately above the fault. (b) Aftershocks may occur, causing more damage to buildings already weakened by the main earthquake.

4. The water displaced by the earthquake moves in short but wide waves in deep water, only increasing in height when close to land.

5. (a) a sudden increase in water level that causes major flooding (b) a sudden decrease in water level that exposes a wide expanse of land 6. Answers should indicate that an earthquake on the ocean floor displaces a lot of water, which travels as a series of waves across the open ocean to shore.

Science as a Human Endeavour question Nature and development of science/Use and influence of science Refer to <http://www.bom.gov.au/tsuanmi/about/atws.shtml> for helpful information about Australia’s tsunami warning system.

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• Earthquakes are most commonly the result of tectonic plate movement along a fault line but they can also be caused by volcanic activity.

• Radioactive decay deep in the Earth’s core powers convection currents that move the tectonic plates at the rate of a few centimetres a year.

• The strength of earthquakes is measured on the Richter scale. The scale relates to the magnitude (the estimated amount of energy released by the earthquake).

• Tsunamis usually follow an underwater earthquake caused by plates pushing together when one plate pushes under the other.

• Useful websites: − <http://aspire.cosmic-ray.org/labs/seismic/index.htm> − <http://science.howstuffworks.com/nature/natural-disasters/ tsunami.htm> − <http://www.weirdsciencekids.com/ TsunamiSimulationExperiment.html> − <http://wcatwc.arh.noaa.gov/> − <http://science.howstuffworks.com/nature/natural-disasters/ earthquake.htm> − <http://www.amnh.org/ology/index.php?channel=earth>

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Earth and space sciences

• The Indian Ocean Tsunami Warning System became active almost two years after the Indian Ocean earthquake and tsunami of December 2004. New technologies for determining the location, magnitude and hypocentre of the earthquake were developed for this system.

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Preparation

Page 45

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• Most destructive tsunamis are caused by earthquakes of magnitude 7.5 or more.

Students should discover that the wave created by striking the top of the table would create a tsunami because it causes the greatest disturbance of water. If this does not occur, they can reflect on how accurately they followed the procedure.

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• Research recently occurring earthquakes and tsunamis and present the information in a table for students to view and discuss.

• Display a world map with tectonic plates and fault lines marked.

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How are earthquakes and tsunamis related? – 1 Earthquakes and tsunamis are both mostly naturally occurring events, both related to the stability of the Earth’s crust.

The Earth’s crust is not one single piece with no joins. It is made of eight large pieces and a number of smaller ones, fitting together like an irregular jigsaw. Each piece is called a tectonic plate. The joins between these plates, known as fault lines, sometimes release the pressure that has been building deep within the Earth. When this pressure is released, the plates move with massive force, causing the ground to tremble. This is what we call an earthquake.

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In a normal fault, plates move apart.

In a thrust fault, plates push together.

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The plates can move in one of three ways.

In a strike-slip fault, plates slide against each other.

© R. I .

C.Publ i cat i ons A tsunami can occur after an earthquake on the ocean floor. As one tectonic plate slides under •f orr evi ew pur posesonl y• another, an enormous amount of water is displaced (pushed). The force of the eruption provides waves slowing down and increasing in height

wave’s length

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energy for the water to travel quickly across the open ocean in a series of waves that remain short but wide while the water is deep. But closer to land, as the water becomes shallower, the waves slow down, are closer together and increase in height. By the time they reach the coast, the waves can be about 20 m high. run-up

crest

normal sea level

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drawback

ocean floor

submarine earthquake

Before the tsunami waves hit the coast, one of two things can happen:

• If the first part of the wave to hit is the trough (the lowest point of the wave), then there is a sudden decrease in water level. This actually exposes a wide expanse of land. This is known as the drawback.

• If the crest (high point) hits first, then there is a large increase in water level, causing major flooding. This is known as the run-up.

If a large tsuanmi hits, there can be multiple waves which hit hours apart.

Unlike a land earthquake where the epicentre is the scene of greatest force, a submarine (underwater) earthquake is barely noticeable at sea. But the devastating effects of a tsunami can be felt thousands of kilometres away.

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The shock waves from the earthquake are the strongest at the epicentre, the land directly above the plate movement. This is where the most destructive force occurs. The waves weaken as they move away from the epicentre. For weeks after a major earthquake, aftershocks of less intensity may be felt. These can cause further damage to buildings and services already damaged by the original earthquake.

How are earthquakes and tsunamis related? – 2 Use the text on page 43 to complete the following.

1. Earthquakes and tsunamis are related to the

1

2

Earthquakes can occur on

of the Earth’s crust.

3

or out at 4

can create a tsunami. Earthquakes occur along the 5

of the Earth’s 6

, when pressure from deep within the

is released.

, which

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2. Describe the ways tectonic plates can move to create an earthquake.

(b) thrust fault

(c) strike-slip fault

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(a) normal fault

3. (a) Would your home likely be more damaged by an earthquake if you lived 1 km or 10 km from its epicentre? Explain your answer.

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4. Explain why a ship on the open ocean that is close to the epicentre of a submarine

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Earth and space sciences

(b)

© R. I .

C.Publ i cat i ons Why might it not be safe to return to your damaged home after an earthquake?

•f orr evi ew pur posesonl y•

earthquake that generates a tsunami would not be affected by the tsunami.

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5. (a) What is a tsunami run-up?

(b) What is a tsunami drawback?

6. Write a brief explanation of how a tsunami is created and how it travels to shore.

Scientists have worked together to devise tsunami early warning systems. Research to find out about Australia’s tsunami warning system.

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How submarine earthquakes can create tsunamis Earthquakes produce primary and secondary seismic waves. Primary waves are longitudinal, causing a backward–forward motion. Secondary waves are transverse, causing a side-to-side motion, or surface, causing an up and down motion. Often, both types of secondary wave occur at the same time. One of these wave types can trigger a tsunami if the earthquake it comes from measures at least 7.5 on the Richter scale.

Follow this procedure to determine which type(s) of wave can create a tsunami.

You will need:

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a clear plastic box water

On the table, half fill the box with water.

a sturdy outdoor table

– front edge to produce a longitudinal wave – side edge to produce a transverse wave – top to produce a surface wave.

Observe what happens to the water after each strike.

Prediction: Record what you think you will see with each strike. front – side –

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a rubber mallet

With the rubber mallet and using an equal force, strike the table on its:

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Earth and space sciences

• • • •

What to do:

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top –

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Results: Describe and draw the wave formations produced after each strike.

Front edge strike – longitudinal wave

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Side edge strike – transverse wave

Top strike – surface wave

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Conclusion: The

wave would cause a tsunami because

.

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How are earthquakes measured?

Content focus: Inquiry skills focus:

• Longitudinal (primary) wave: the operator pushes the slinky once towards the holder.

Richter and Mercalli scales for measuring magnitude of earthquakes

• Transverse wave (secondary 1): the operator waves the slinky once from side to side.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Surface (secondary 2): the operator lifts the slinky up and snaps it down once.

Answers

r o e t s Bo r e p ok u S Page 48

1. (a) Richter: the total energy released by the activity of the tectonic plates. Mercalli: the structural damage and landscape changes caused by the earthquake (b) For each value on the Richter scale, the intensity of seismic activity increases tenfold. (c) The Richter scale measures a definite value. The Mercalli scale describes what was felt and seen, which can be interpreted differently by different people.

2. Deep peaks and troughs indicate intense seismic activity; i.e. a high-magnitude earthquake; shallow ones indicate slight activity or a low-magnitude earthquake.

3. (a) Primary waves shake the ground back and forth. Secondary waves shake the ground up and down and from side to side. (b) It would show the secondary waves arriving some time after the primary waves, because they travel slower.

4. If the hypocentre of the lower magnitude earthquake was closer to the surface, it would create more damage and be given a higher Mercalli rating.

Science as a Human Endeavour question Nature and development of science/Use and influence of science.

In 2008, Professor Brian Kennett was awarded the Gold Medal for Geophysics from the Royal Astronomical Society in London for research in the area of predicting earthquakes.

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• Seismic activity occurs as tectonic plates slide over the layer of magma beneath them. When this activity becomes intense, earthquakes occur. The Richter scale is an objective, logarithmic measure of the total energy released by an earthquake. The Mercalli scale is a subjective measure describing the destruction caused by earthquakes of different intensity. Because the depth at which an earthquake occurs affects the resulting damage, the two scales are not necessarily linked. The location of the earthquake also affects the amount of destruction; for example, the damage to a highly populated urban area can not be compared to a remote, sparsely populated area.

• There are two types of seismic wave that are produced by the energy released from an earthquake.

Page 49

Preparation

Teacher check

• Print out and enlarge descriptions of the Richter and Mercalli scales.

Research recent earthquakes, along with their Richter and Mercalli scale measurements.

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• Collect a number of slinky springs for maximum student participation in wave demonstration.

The lessons • Pages 47 and 48 should be used together.

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• Useful websites: − <http://earthquake.usgs.gov/learn/kids/eqscience.php> − <http://sunshine.chpc.utah.edu/labs/seismic/index.htm>

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• Longitudinal (primary) waves move the ground backwards and forwards. Transverse waves move the ground from side-to-side, while surface waves cause an up and down motion. Both types are considered secondary types.

• Discuss the Richter and Mercalli scales. They can often be found side by side. Discuss why this can only be a general relationship as the scale of destruction is dependent on other factors.

• Using a slinky spring, demonstrate the primary and secondary types of seismic wave. Stretch the spring to about eight times its compressed length. Two students each hold one end. One student is the ‘holder’ while the other is the operator’. The holder holds the slinky firmly as the operator creates the waves.

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How are earthquakes measured? – 1 The strength or magnitude of an earthquake is measured in two ways. Firstly, by the total energy released by the activity of the tectonic plates, and, secondly, by the structural damage and landscape changes the earthquake creates.

When an earthquake occurs, it releases a massive amount of energy. This energy creates seismic waves that radiate away from the fault in all directions. The earth shakes as the waves travel through it, and on the surface the ground begins to break apart. The intensity of the seismic waves can be recorded on a seismograph. Shallow peaks and troughs on the graph indicate a low-magnitude earthquake. Deep peaks and troughs indicate one of higher magnitude.

r o e t s Bo r e p ok u S wave direction

compressions

compressions

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At the epicentre of an earthquake, the ground can been seen as moving back and forth and up and down and/or side to side at the same time. A seismograph located at the epicentre will show both primary and secondary wave types occurring at the same time. At locations further from the epicentre, seismographs will show secondary waves arriving after primary waves because they travel slower.

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The Richter scale gives an earthquake a value from zero upwards (usually between zero and ten). It is based on information recorded by seismographs. The Richter scale is a base 10 logarithmic scale. This means that every whole number jump on the scale represents a tenfold jump in the intensity of seismic activity. An earthquake that measures 7 on the Richter scale is ten times greater in magnitude than one that measures 6 (and one hundred times greater than one that measures 5).

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As an earthquake strikes, it creates most devastation at the epicentre. This lessens as the distance from the epicentre increases. The effect of the earthquake can be described and matched to a scale that indicates what was felt and what damage was done when the earthquake struck. This is known as the Mercalli scale. It has 12 levels of intensity. At Level One, little, if anything, is felt or seen. At Level 12, massive shaking occurs and widespread destruction happens.

The Mercalli scale measurement of an earthquake often does not match the Richter scale magnitude because there are other factors to consider which may increase or decrease the scale given. These include the density of population of the affected site and the depth below ground where the fault line began to rupture (which is known as the hypocentre).

This distance below ground can be calculated by seismologists, who study the length and intensity of the seismic waves the earthquake produced. The closer to the surface the hypocentre is, the greater the damage. It is possible for a strong earthquake with a deep hypocentre to cause much less damage than a weaker earthquake with its hypocentre closer to the surface.

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wave direction

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There are both primary and secondary seismic waves, each shaking the ground in different ways. Primary waves, which travel faster, shake the ground back and forth. Secondary waves shake it up and down and side to side.

How are earthquakes measured? – 2 Use the text on page 47 to complete the following.

1. (a) Complete the table to describe the two scales of measurement of earthquakes. scale

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(c) Why are the two scales not truly compatible?

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(b) The Richter scale is a base 10 logarithmic scale. Explain what this means.

2. A seismograph records the movement of the earth during an earthquake. How do the peaks and troughs match the magnitude of the earthquake?

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3. (a)

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(b) At the epicentre of an earthquake, the two types of seismic wave are recorded at the surface at the same time. What would a seismograph located 10 km from the epicentre show and why would this happen?

4. Why might an earthquake with a lower magnitude on the Richter scale have a higher Mercalli scale level?

Earthquakes can not be predicted, but scientists are trying to find clues that will help them do this.

Research to find out about Professor Brian Kennett of the Australian National University.

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Earthquake research Earthquakes have always been a part of the geological life of planet Earth, but it has only been since 1935 that the Richter scale has been used to measure them.

Research the five largest earthquakes to have been recorded on the Richter scale. Use information from a number of sources to complete the table.

2.

Hypocentre depth

Direct damage

Additional effects

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Total fatalities

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Richter scale reading

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How are volcanic eruptions monitored?

Content focus: Inquiry skills focus:

Answers

Monitoring volcanoes to predict eruptions

Page 52 1. Monitoring volcanoes provides scientists with useful information to help them predict when a volcano is getting ready to erupt so people can prepare to evacuate.

2. With future eruptions, people will know how far from the volcano volcanic deposits will fall. This determines how far away people will need to travel to be safe from the deposits.

3. (a) spectrometer (b) seismometer (c) tiltmeter/geodimeter 4. magma 5. (a) false (b) false (c) true 6. You would alert authorities to follow an established action plan as soon as possible. Reduced gas emissions means that gas escape routes may have been blocked and pressure is building. If an eruption occurs, it is likely to be explosive.

7. The land around volcanoes is very fertile due to mineral deposits from volcanic eruptions. The risk of danger is offset by the benefits for farming.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• Because earthquakes are related to volcanic activity, seismology can be used to detect frequent earth tremors that can indicate the possible eruption of a volcano. These vibrations, known as volcanic tremors, are the result of interactions between magma and rocks in the Earth’s crust. People living within range of an active volcano may be familiar with volcanic tremors as they can cause buildings to shake. The signal of a volcanic tremor has been used to predict the eruption of some volcanoes where monitoring is in place; for example: Mt Redoubt in 1989 and Popocatépetl in 2000.

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Science as a Human Endeavour page Use and influence of science Teacher check A list of volcanic eruptions may be found at websites such as <http://www.infoplease.com/ips/A0763388.html>.

Students should expand on these by researching each volcanic eruption specifically.

• The purpose of monitoring volcanoes is to be able to inform those living near them of the possible event of an eruption. Communication among scientists, officials and the community, and the development of an emergency plan, is essential if lives are to be saved.

Preparation

The lessons

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• Two helpful resources which the teacher may need include a large colour map of the Pacific Ring of Fire with notable volcanic eruptions marked, and a large map showing the tectonic plates in the same region.

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• Useful websites: − <http://www.weatherwizkids.com/weather-volcano.htm> − <http://www.geo.mtu.edu/volcanoes/hazards/primer/>

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• Discuss why people might choose to live near a known active volcano.

• Discuss and make a list of the criteria that is used to predict volcanic eruptions. Revise the movement of tectonic plates and causes of seismic activity from pages 38–41. For the activity on page 53, students will require access to the internet.

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How are volcanic eruptions monitored? – 1 small but measurable volcanic tremors, which can be detected and measured on a seismometer. People living within range of a volcano will be familiar with volcanic tremors as they often cause buildings to shake. The signal of a volcanic tremor has been used to predict the eruption of some volcanoes where monitoring is in place; for example: Mt Redoubt in 1989 and Popocatépetl in 2000.

After an eruption, the areas affected by volcanic deposits such as ash and rock are mapped and recorded. This tells scientists how extensive the volcano’s damaging coverage is, and so how far from the volcano protective measures need to be taken in case of a future eruption.

Even though scientists might be able to predict an eruption, they can not say exactly when it will occur. Volcanoes are unpredictable. Sometimes the magma in a chamber may not erupt; it may just cool below the surface. At other times just before an eruption, the volume of sulfur dioxide gas released may decrease. In such cases, scientists believe the magma seals the passage ways through which the gas usually escapes. This causes a build up of gas pressure and increases the chance of an explosive eruption.

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The magma can also cause the slopes of a volcano to bulge. This swelling can be detected with a tiltmeter and a geodimeter.

In the event of another eruption, an alert system can be used to inform communities of its progress and the expected dangers.

If necessary, the people living within areas affected by volcanic deposits can be evacuated.

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By monitoring volcanoes, scientists are learning more about ‘the enemy’, but it is not possible to monitor every single active volcano. It would be very expensive as there are far too many volcanoes. Many people choose to live close to volcanoes because the land around them is rich in mineral deposits and good for farming. For some people, the risk of danger is the price they pay.

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Scientists are also attempting to recognise the warning signs of an upcoming volcanic eruption. If an active volcano is in a highlypopulated area, they will monitor and record the volcano’s activity. Any changes to the norm may indicate that an eruption could soon occur.

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One warning sign is an increase in the area of the gas sulfur dioxide. A strong-smelling gas, increases in its release can be detected by a machine called a spectrometer.

Another sign is an increase in seismic activity in the area. As magma collects in chambers before an eruption, it creates changes within the volcano. This can cause

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A famous military quote suggests that the best way to defeat an enemy is to know the enemy. By understanding how natural disasters occur, we can attempt to manage the dangers they bring. Volcanologists study volcanic eruptions so they can predict when they might occur again. This knowledge could be vital for saving the lives of the people who live close to their fertile slopes, giving officials time to put communities on alert and engage action plans for everyone’s safe evacuation.

How are volcanic eruptions monitored? – 2 spring

Use the text on page 51 to answer the questions.

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1. Why is it useful for scientists to monitor volcanoes?

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3. Match each volcanic feature with the instrument(s) used to measure it.

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2. How can mapping areas affected by volcanic deposits help to save lives?

(a) Release of sulphur dioxide gas •

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(b) Volcanic tremors

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(c) Volcanic bulging

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4. Add the missing word to complete the sentence.

5. Answer as true or false.

(b) Volcanoes always behave the same way. (c) Moving magma can cause the slopes of a volcano to bulge.

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(a) Magma that has collected in a chamber always erupts.

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As collects in chambers before an eruption, it creates changes which can cause volcanic tremors.

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6. If you were a scientist monitoring the amount of sulfur dioxide gas being released from a volcano and you noticed a drop in the amount of gas being released, what would you do?

Explain why.

7. Why do you think people (especially farmers) choose to live close to volcanoes even though they can be dangerous?

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Ring of Fire eruptions In December 2000, scientists predicted the eruption of Popocatépetl, just outside Mexico City. The government ordered the evacuation of tens of thousands of people.

Two days later, the volcano erupted. It was the volcano’s largest eruption for over one thousand years. There were no casualties.

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Find information about four volcanic eruptions that have occurred in the Ring of Fire within the past 50 years. Mark each on the map.

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Facts and figures about the volcano, its eruption and aftermath

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Volcano’s name, location and date of eruption

SOUTH AMERICA

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Popocatépetl lies within the Pacific Ring of Fire, a 40 000 km-long ‘ring’ that hugs the Pacific coastal regions of both Americas, Russia, China, Japan, Indonesia, New Guinea, the Pacific islands and New Zealand. Its intense seismic activity is due to the movement and collisions of the Pacific Plate and other major tectonic plates.

What are the effects of drought?

Content focus: Inquiry skills focus:

Answers

Effects of drought on living and nonliving aspects of the environment

Page 56 1. Answers should be similar to: A drought is a time of no rainfall, which reduces water availability so that there is not enough water for everyone and everything that needs it.

2. A famine happens when the sources of food are destroyed. During a drought, crops and other plants can not grow because they have no water. People and animals relying on the food grown are instead left hungry.

3. Because the human body is between 55% and 65% water, it needs water to work properly. If we do not drink enough, our water levels drop and our organs can not work well and they can fail.

4. Lack of water for personal hygiene and sanitation means that disease causing microbes can thrive. Famine-affected people are more likely to be infected because their bodies are already weak from hunger.

5. The students could draw a variety of different charts to answer this question. The charts should include: Drought: no rain, plants and crops die, no food, animals die, people die Drought: no rain, loss of fresh drinking water, loss of water for personal hygiene and sanitation, rise in population of disease-carrying microbes, infection and death of people weakened by hunger Drought: no rain, plants and crops dry out, fire Drought: no rain, habitats destroyed, reduced biodiversity, unbalanced food webs, reduced seed dispersal and pollination Drought: no rain, plants and crops die, roots don’t hold soil, soil erodes, soil unable to sustain future growth Science as a Human Endeavour question Nature and development of science/Use and influence of science Websites such as <http://www.abc.net.au/catalyst/stories/2714955. htm> or <http://weatherquestions.com/What_is_cloud_seeding.htm> can provide useful background information for students.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• Many scientists study the effects of drought in high risk areas. They study the patterns of rainfall across seasons and over years, the impact of drought on major industries, groundwater and reservoir levels, and the personal effect on society.

• Australia’s location makes it susceptible to droughts as it is in an area which is influenced by a subtropical high pressure belt. In this area, cool, moist air sinks towards Earth. As it sinks, the air warms up and dries out. This creates stable areas of high air pressure with cloudless skies and little rainfall.

• Useful websites: − <http://www.bom.gov.au/climate/drought/livedrought.shtml> − <http://www.actnow.com.au/Issues/Drought.aspx> − <http://home.iprimus.com.au/foo7/droughthistory.html>

• From local councils, obtain water restriction calendars. From hardware store catalogues, collect image examples of rainwater tanks.

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• Obtain information about local, national or international water recycling and desalination plants.

The lessons

• Pages 55 and 56 should be used together.

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• Collect pictures of drought affected areas. Provide a map of the world with drought prone areas highlighted. Research significant worldwide droughts within the last 30 years and the national and international agencies that have helped those badly affected by them.

Include the global phenomena of Band Aid and Live Aid.

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• Discuss students’ knowledge of drought conditions. Record all relevant points made. Discuss the difference between drought conditions in the students’ home country and those in other parts of the world. How and why do the effects and consequences compare or not compare?

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What are the effects of drought? – 1 Both water and air are important for life on Earth.

Imagine having no air to breath. Having no water may not be as immediately drastic but, before long, the same result occurs—death! If there is a lack of rainfall, this can mean there is not enough water to supply all those who need it, including animals and plants. When little or no rain falls over a long period of time in an area, it is said to be suffering from drought.

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Hunger and famine

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You may think, ‘Don’t waste precious water on plants—humans and animals are much more important!’ But did you know that plants are the foundation of all food webs? If they die because they are deprived of water, everything else in the food web will also suffer. When food crops fail because of lack of water, people and animals are left hungry. If a drought continues, famine will occur and people may die.

Loss of fresh drinking water

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Droughts f or evdisease-carrying i ew pur pos es on l y• usually occur in hot regions and the high temperatures can also help the microbe population to Spread of disease

soar. Famine-affected people may be even more susceptible to disease, as they are already weakened by hunger.

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Suffering environment

When a drought occurs, it is not just the living that are badly affected. The environment also suffers and this has consequences for its ability to sustain life:

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Fires increase in frequency and severity, fuelled by the tinder-dry plant life.

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The loss of plant life and the roots that hold soil in place can leave the soil susceptible to erosion by wind and, when rains finally do fall, by water. This means the soil will no longer be able to sustain healthy plant life.

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Animal habitats are also lost and this leads to a reduction in biodiversity, which can affect the balance of food webs as well as seed dispersal and pollination.

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Many of the countries where droughts are more likely are underdeveloped and politically unstable. This means that when a natural disaster such as a drought occurs, the victims may have to rely on help from other countries.

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The human body is between 55% and 65% water. When you start to feel thirsty, you are already starting to dehydrate. Your body is functioning at much less than 100% capacity because your organs are struggling to work efficiently. They need water. It is possible to survive a few weeks without food but a person can only survive a few days without water.

What are the effects of drought? – 2 Use the text on page 55 to complete the following.

1. In your own words, describe what a drought is.

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3. Why is important to keep your body hydrated?

4. Why can disease spread easily in drought stricken areas?

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2. How does a famine occur?

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5. Draw a chart to show the main effects of drought.

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Do you really think that scientists or other people can really make rain fall? Type ‘cloud seeding’ into a search engine and learn about this amazing artificial technology!

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Clean water for all!

Water is one of our most precious resources. It is constantly recycled and is present today in the same quantity as it has been since the planet was formed, approximately 4.5 billion years ago.

But it is not always available in the right form and in the right place where it is needed.

Steps can be taken to make sure there is enough water available for all so that no-one has to suffer the horrors of drought.

1. (a) Research some ways by which we can work towards ‘water for all’. (b) Discuss your information with a partner or in a group.

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(c) Record your information in the table.

2. Share your information with other pairs or groups.

Advantages

Disadvantages

Rainwater harvesting

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Water restrictions

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How does it work?

How does electricity flow?

Content focus: Inquiry skills focus:

the others, the switch is closed and the current flows. When he or she steps out of line, the flow stops. Each student is an atom of the metal wire. Give each a ball which represents the electrons in the outer shell of each atom. When the switch is closed, each student passes his or her ball forward with the left hand, receives the ball from behind in the right hand and transfers it to the left hand before passing it on. On command, the switch steps out of line and all ball movement must stop.

A complete circuit is needed for electricity to flow Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• If students have difficulty making the activity on page 61 work, they can consider how accurately they have assembled each circuit and the possibility that the batteries may have run down or the globes have blown.

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Page 60

1. (a) The current will not flow because there is a break in the circuit. (b) The current will flow because there are no breaks in the circuit. (c) The current will not flow because there is a break in the circuit as the switch is open.

2. (a) electrons – negatively charged particles (b) current – the flow of electrons from one atom to another (c) resistance – the force that acts against the flow of electrons (d) load – something that uses electricity (e) voltage – the force that pushes electrons around a circuit 3. (a) False (b) True (c) True 4. (a) Electrons flow from the negative end of the battery, through a circuit to the positive end. (b) Answers should be similar to: the negatively charged electrons are pushed from the negative end of the battery, through a circuit and return to the positive end of the battery.

Science as a Human Endeavour question Nature and development of science/Use and influence of science Students can complete the activity using their own general knowledge or by researching the information.

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• Electrons in the outer shell of each atom in a metal wire are not fixed to a specific atom. When a circuit is complete and the battery provides the force (voltage) for the electrons to flow, the electrons in the outer shells move from one atom to the next. They continue to travel in this way until there is a break in the circuit and the flow stops.

• Household wiring can be arranged as series and parallel circuits.

From the mains to the meter box, the circuit is in series. This is why when there is a power cut, there is no power to the house, and when an electrician is working in the house, he or she can turn off the mains switch and know for sure that there is no power.

• Students may notice the difference in light intensity of the globes in each circuit. The flow of electricity is affected by the resistance within the circuit. All globes act as resistors. In a series circuit, there is twice as much resistance so each globe is half as bright as a single globe in series would be. In a parallel circuit, each globe has its own circuit branch and the resistance for each is the same as for a single globe in series so each globe glows equally brightly.

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• Useful websites: − <http://www.electrickids.com.au> − <http://www.eia.doe.gov/kids/energy.cfm?page=electricity_ home-basics> Preparation

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1. Hypothesis/Results Switch 1 – This is a series circuit and the current has only one path along which to flow. When the switch is turned off, both bulbs go out because there is no longer any current flowing.

Switch 2 – This switch is arranged in series so when it is switched off, neither globe will work because the current has stopped flowing.

When it is turned on, the globes will only work if their switches are also turned on.

Switches 3 and 4 – These are arranged in parallel with their globes.

If they are turned on, the globes will work if switch 2 is also turned on. If it isn’t, neither globe will work. If either switch is turned off, the other will still work if switch 2 is turned on.

2. Switch 1 – series; Switch 2 – series; Switch 3 – parallel; Switch 4 – parallel 3. Answer should be similar to: electrical components arranged in series will only work if there are no breaks in the circuit. Arranged in parallel, the components can work independently of one another.

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• Two A4 cards, one with ‘positive (+)’ and the other with ‘negative (–)’ written clearly in the centre. Small balls, enough for one per student.

• Teachers will need to collect the electrical components as listed on page 61.

Physical sciences

The lessons • Pages 59 and 60 should be used together.

• The most important thing for students to understand is that electricity travels as a continuous flow of electrons. If there is a break anywhere in the circuit, the electrons (and hence electricity) will cease to flow.

• The movement of electrons in a circuit can be demonstrated. Students stand in a circle, all facing the same direction. Nominate one student to be the battery. This student wears a large positive sign (+) on his or her back and a large negative sign (–) on the front. Nominate one student to be the switch. When the ‘switch’ student stands in line with

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How does electricity flow? – 1 Imagine riding a bicycle on a path around a lake. If there are no obstacles on the path, you can easily complete the circuit and end up back where you started. In the same way, if there are no breaks in an electrical circuit, a current will start at a battery and flow around the circuit until it is back at the battery. If when cycling an obstacle falls on the cycle path behind you, it won’t stop you completing the circuit because you have already passed that point. However, if a break occurs anywhere in an electric circuit at any time, the electricity stops flowing.

On the bicycle path, there may be a tunnel to ride through or a bridge crossing over a stream, but these won’t stop your progress. In an electric circuit, there may be a light globe or a door bell that uses the electricity but, like the tunnel or the bridge, they do not stop the flow of electricity.

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Electric current

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Perhaps a train line crosses the cycle path. When a train is due, warning lights flash and a gate comes down across the path, blocking the way. Until the train has passed and the gate is lifted, you will not be able to continue. A switch in an electric circuit is like that gate. It stops and starts the flow of electricity.

Electric circuit

Everything is made up of atoms, each of which has a positively charged core (called a nucleus) and number of concentric shells surrounding it. These shells contain tiny negatively charged particles called electrons.

In metals, electricity is the flow of electrons from the outer shell of one atom to the outer shell of another. This flow of electrons is called a current. The path of the current is called a circuit.

A simple circuit consists of a battery to provide power, wires to carry the current and a load that uses the electricity; for example, light globe.

The wires are connected from the positive end to the negative end of the battery. In between, a light globe is attached. A switch can be added to create or break the circuit so the globe can be switched on and off.

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Resistance

To make the electricity flow, a force is needed to push the electrons around the circuit. This force, which is called the voltage, is provided by the battery. The electrons flow from the negative terminal of the battery, along a wire to the load, then along another wire to the positive end of the battery.

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As a current flows through a circuit, the wire exerts a force against the flow of electrons. This force is called resistance. It causes friction by slowing down the movement of electrons.

A thin wire slows the electrons more than a thick wire and creates more resistance. This is the same for the longer wire.

It takes energy for electrons to move against the resistance along a wire.

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How does electricity flow? – 2 Use the text on page 59 to complete the following.

1. For each circuit, state whether the current will or will not flow. Explain why or why not. +ve

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The current will/will not flow because ...

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the force that pushes electrons around a circuit

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negatively charged particles

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(d) load (e)

•

3. Tick as true or false.

True

False

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(b) More energy is lost in a longer wire than a shorter wire.

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(c) A thick, short wire has less resistance than a thin, long wire.

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(a) Electrons pass more easily along a thin wire than a thick wire.

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4. In an electric circuit, electrons flow from the battery in one direction only.

(a) Tick which you think is the correct end to the statement. Electrons flow from ...

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•

the positive end of the battery, through a circuit to the negative end.

•

the negative end of the battery, through a circuit to the positive end.

(b) Rewrite the correct sentence in your own words.

List different ways electricity is used at home and in the wider community.

Show your information in a table, then compare it to that of another student and include any additional information to your own.

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Connecting circuits Electrical circuits can be connected in two ways: Series

Parallel

In a series circuit, the current flows along a single path from the battery, through each component in turn and back to the battery.

The current in a parallel circuit can flow along more than one path and through the components in each branch of the circuit at the same time.

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You are going to investigate both types of circuit.

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You will need:

battery

â&#x20AC;˘ 2 batteries

â&#x20AC;˘ 4 light globes

â&#x20AC;˘ 4 switches

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â&#x20AC;˘ Set up each circuit as shown in the diagrams.

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í˘´

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C.Publ i cat i ons what you think will happen to each globe when each switch is opened and closed â&#x20AC;˘f orr evi ew pur posesonl yâ&#x20AC;˘ what happened to each globe when each switch was opened and closed.

í˘ą In the table, record:

Switch

(a) Prediction

(b) Results

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2 3 4

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1

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í˘˛ Write either series or parallel to indicate how each switch is connected.

Switch 1

Switch 2

Switch 3

Switch 4

í˘ł What can you conclude from this investigation?

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(b)

closed switch

light globe

â&#x20AC;˘ 13 connecting wires

What to do:

(a)

open switch

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What are electrical conductors and insulators?

Content focus: Inquiry skills focus:

• Materials that did not conduct electricity in the first part of the test can be used as insulators in this part. Ask: How will they determine which conductor to use? Does it matter? How will they cover the conductor with the insulator? How will they ensure a fair test?

With some insulating materials, covering the conductor may pose problems. Ask: How will they overcome these problems? In their evaluations, students can discuss practical points that may have helped or hindered their investigations.

The difference between electrical conductors and insulators Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

r o e t s Bo r e p ok u S Answers

Page 64

Background information

1. (a) true (b) false (c) true (d) false 2. The electrons in the outer shell are held firmly in place and do not move from one atom to another when an electrical force is applied.

3. Copper is less expensive than silver and it is almost as good as silver at conducting electricity.

4. Water is a good electrical conductor and the human body is about 55% to 65% water.

5. (a) They cover copper wires that carry electricity, preventing the current from passing to us or any other conducting material. (b) Bare copper wire is first covered with an insulating sheath made of plastic. Lengths of wire are then insulated together in a thick, plastic outer cable.

6. (a) For electricity to flow, a circuit must be complete. The brass pins make the connection between the wires in an appliance cable and the wires between the socket and the source. If they were insulated, the pins would not be able to make this connection. (b) To prevent anyone putting something (which may conduct electricity) in them and getting electrocuted.

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• Ensure students understand the meaning of resistance. Refer to page 59. It is a force that acts against something. In electricity, resistance acts against the flow of electrons. It slows them down and doesn’t want them to pass through. Electrical conductors have a low resistance to the flow of electrons, which means they allow electrons to flow easily.

Insulators have a high resistance to electron flow. Effective insulators can halt the flow of electrons, stopping them completely.

• Useful websites: − <http://www.electrickids.com.au> − <http://www.ndt-ed.org/EducationResources/HighSchool/ Electricity/conductorsinsulators.htm> Preparation

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• Bring to the lesson two- and three-pin plugs, including those that can be pulled apart; lengths of copper wire; insulated wire (blue, brown, yellow/green); and outer cables.

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• Pages 63 and 64 should be used together.

Page 65 At the conclusion of the activity, the students will be able to name types of material that conduct electricity and those that do not. They will discover that some insulators are far more effective than others. Water and metals are generally good conductors, while good insulators include cotton, rubber, glass, porcelain, paper, wood and fibreglass.

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The lessons

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• For the activity on page 65, provide sufficient electrical components: batteries, insulated wires with connecting clips, light globes and/or other loads, and switches. Materials for testing can include: different metals, steel wool, water, graphite from pencils, charcoal, chalk, polystyrene (trays), cottonwool, plastic, chipboard, ceramic, slate, bark, different fabrics.

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• Allow students to cut outer cables to see the coloured insulation inside and then cut this to reveal the copper wire. Ask: Why is the copper wire in thin threads and not in one solid piece? Students can pull the plugs apart and see the different coloured wires connected to the live, neutral and earth pins, noting that only bare copper wire is part of the connection.

SAFETY FIRST: Ensure no student plugs an uncovered plug into a socket.

• Discuss students’ ideas for each part of the investigation on page 65.

Guide them towards connecting each material in turn to a circuit. If the material allows electricity to flow, it is a conductor. If it does not, it is an insulator. Ask: How will they know if electricity is flowing? (They will need to incorporate a load, such as a light globe or bell, into the circuit.) It may be possible to determine an order of effectiveness of the conductors by how well the load works.

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What are electrical conductors and insulators? – 1 Some materials have a low resistance to electricity and will allow it to easily pass through them. These are called electrical conductors. Electrical insulators are materials that have a high resistance to electricity and won’t allow it to flow through them. Some materials are better as conductors and some better as insulators. So what makes a material one or the other?

r o e t s Bo r e p ok u S

Teac he r

Did you know that the human body is a good conductor of electricity? Water is a good electrical conductor and the human body is about 55% to 65% water! This is why it is important to never plug in an electrical appliance if your hands are wet or if you are standing in water.

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All materials are made up of atoms. These are tiny particles, each with a positively charged core called a nucleus with a number of concentric shells surrounding it. The shells contain tiny negatively charged particles called electrons. In all but the outer shell, the electrons are held securely in place. In materials that are good electrical insulators, the electrons in the outer shell are also held firmly. But in some materials, the electrons in the outer shell are held only loosely. These electrons easily flow from one atom to another when an electrical force (voltage) is applied. Metals are examples of this type of material and many metals are good electrical conductors.

The strength (voltage) of electricity supplied to our homes is very low compared to the voltage in power lines, but at 220–240V it is still deadly.

So how are we able to use electricity safely?

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C.Publ i cat i ons copper wire used for carrying electricity is •f orr evi ew puBare r p os sonsheath l y• enclosed ine a protective made from an electrons

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inside an atom

insulating material, usually plastic. The sheath stops the electricity escaping from the wire and flowing through any other conducting material.

The wire in the sheath is then insulated in a thicker outer plastic cable.

Household appliances have at least two lengths of wire within the outer cable. The ‘live’ wire is in a brown sheath and the ‘neutral’ wire is in a blue sheath. A third, ‘earth’ wire in a yellow/ green sheath can also be included.

o c . che e r o t r s super shells

electrons in orbit

nucleus of the atom

Although silver is the best conductor of electricity, it is very expensive. Copper is almost as good a conductor and much cheaper than silver, so copper wiring is often used in electrical appliances and to conduct electricity from one place to another.

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Wires are encased in insulating material to protect us from electric shock or even death, so if you can see any exposed copper wiring in a cable at home, maybe it’s time to replace it!

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nucleus of the atom

What are electrical conductors and insulators? – 2 Use the text on page 63 to complete the following.

1. Answer as true or false. (a) Good conductors have a low resistance to electricity. (b) Insulators allow electricity to flow through them.

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(c) Electrons in the outer shell of conductors are held loosely. (d) Electrons in the outer shell of insulators are held loosely.

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2. Explain why insulating materials do not conduct electricity.

3. Why is copper used instead of silver in electrical wiring?

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4. Why is the human body a good electrical conductor?

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(b) Describe how bare copper wire in appliance cables is insulated.

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5. (a) How do insulating sheaths protect us from electrocution?

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6. (a) If all the wires in household circuits are insulated for safely, why do you think the brass Physical sciences

pins on an electric plug are not?

(b) Why do you think people put plastic covers on sockets that are not being used?

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Conductor or insulator?

All materials are either conductors or insulators of electricity.

You are going to plan and then carry out a two-part investigation.

1. Test a number of materials to determine if they are conductors or insulators.

2. Determine which materials are the most effective insulators.

What equipment will you need?

Part One:

Part Two:

Method – what will you do?

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Teac he r

What materials will you test?

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C.Publ i cat i ons •f orr evi ew pur posesonl y• Part One:

Part Two:

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Conclusion – What have you learned?

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Evaluation – How do you rate your investigation?

Communicating – How will you present your information?

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How will you present your results?

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Hypothesis – Explain what you expect to discover.

How do light globes work?

Content focus: Inquiry skills focus:

The lessons

The features of some electrical devices: globes and electromagnets

• Pages 67 and 68 should be used together.

• Bring to class clear incandescent and different shaped fluorescent globes for students to look at. Study the component parts that can be seen; but SAFETY FIRST: do not deliberately break any.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• After reading the text, indicate the process on the prepared diagrams. Discuss government proposals to phase out incandescent globes in favour of fluorescent ones. What are the advantages and disadvantages of both?

r o e t s Bo r e p ok u S

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• Thomas Alva Edison is credited with being the inventor of the first practical incandescent light globe, which is still used today. Students may wonder why, in an incandescent globe, it is necessary to coil a long piece of tungsten wire. Why not simply use a short length? The answer is related to resistance. Resistance slows the flow of electrons but it does not stop them colliding with atoms, the activity which releases energy. The longer the wire, the greater the resistance so the slower the flow of electrons and the greater the build up of energy.

Initially, this energy is just in the form of heat. When the temperature is hot enough, over 2000 ºC, approximately 10% is released as visible light energy. The wire needs to be coiled so that a high enough temperature can be reached for visible light energy to be released.

Answers Page 68

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• Before commencing the activity on page 69, revise the basic principles of magnetism, including how opposites attract and likes repel, and that some materials can be magnetised by stroking it with a permanent magnet. Also revise the stages of investigations: questioning, predicting, planning, fair testing, observing, recording, analysing, concluding, evaluating, communicating. How are they going to do each of these?

1. incandescent, fluorescent 2. argon 3. Glass does not conduct electricity and will not interfere with the electric circuit.

4. (a) false (b) true (c) false 5. It is a liquid at room temperature. It is poisonous.

6. (a) ultraviolet light (b) The phosphor absorbs the invisible ultraviolet light and emits visible light.

7. A large force between the electrodes attracts electrons through the gas from one electrode to the other.

8. (a) a build-up of electric current (b) A ballast controls the flow of electrons, stopping the current from becoming too high.

9. Most of the energy released in a fluorescent globe is converted to visible light.

Science as a Human Endeavour question Use and influence of science Teacher check. Students may wish to research some existing signs, posters or warnings for inspiration.

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• The electrons that flow in a current come from the outer shell of the atoms of the conducting metal. With greater resistance, as heat is produced and the atoms vibrate, electrons in the shell beneath the outer shell start to collide with those in the outer shell. As the lowershell electrons fall back into their original places, they release extra energy in the form of light. At lower temperatures, the light emitted is invisible infrared light, but as the temperatures increase, it is visible blue light.

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• All light globes are sealed and the air replaced with argon, an inert gas that does not react with any elements. In the presence of oxygen, the filament in an incandescent globe would burn out before reaching the temperature required for releasing visible light energy.

• In an incandescent globe, the wires supporting the filament and those carrying the electric current are supported by a glass mount. Glass is an electrical insulator, unable to conduct electricity and interfere with the electric circuit.

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• Useful websites: − <http://www.1728.com/project2.htm> − <http://education.jlab.org/qa/electromagnet.html> − <http://science.howstuffworks.com/electromagnet.htm>

Page 69

1. Teacher check 2. Students should discover that: (a) the greater the number of coils, the stronger the electromagnetic field produced (b) the thicker the core, the stronger the electromagnetic field produced (c) only some metals can be used as the core (those which can be magnetised) (d) the greater the voltage, the stronger the electromagnetic field produced.

Preparation • Prepare large, coloured flow diagrams describing what happens within each type of globe when electricity is flowing.

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How do light globes work? – 1 There are two types of globes we can buy for our lights at home: the traditional incandescent globe and the more energy-efficient fluorescent globe.

Incandescent globe glass case

Fluorescent tube

inert gas

electrode tungsten filament

pins

phosphor coating

electrode argon gas

pins

support wires

r o e t s Bo r e p ok u S glass mount

contact wires

AC supply

electrical foot contact

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Teac he r

screw thread contact

mercury

ballast

The components of an incandescent globe are housed in a sealed glass case containing a gas called argon. The metal filament coil is about 2.5 cm long. It is made from two metres of extremely thin tungsten wire. To fit into the space, the fine strip of wire is wound into a tight coil which is then wound around itself to make an even tighter coil.

A fluorescent light globe is a sealed glass tube filled with argon and containing a small amount of mercury, a poisonous metal that is a liquid at room temperature. The glass tube can be a long strip, circular or coiled to fit in standard lamp fittings.

There is an electrode at each end of the tube. When the globe is switched on, a large force between the two electrodes attracts electrons through the gas, from one electrode to the other. As the current flows, heat is produced which turns the mercury into a gas. When electrons and argon atoms collide with the atoms of mercury gas, energy is released in the form of ultraviolet light which the human eye can not see.

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The filament is supported by two wires connected to a glass mount, and two stiff contact wires that form part of the circuit.

Current flows from the circuit through one contact, up the stiff wire to the filament, then down the stiff wire to the other contact and back into the circuit.

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However, the inside of the tube is coated with a layer of phosphor, a substance which can store energy and release it as light. The phosphor absorbs the invisible ultraviolet light and emits a bright visible light. The colour of the light can be varied by using different amounts of phosphor.

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As the electrons flow through the filament and crash into the tungsten atoms, they release energy so the filament gets hot.

The resistance of the coiled thin wire slows the flow of electrons and the energy that is released by the bombardment of atoms increases.

Most of the energy released in a fluorescent globe is converted to visible light energy.

A ballast controls the flow of electrons through the gas. When a current flows through gas, there is not much resistance to the flow of electrons and the current can build up. This would cause the globe to blow; however, the ballast corrects this problem.

Only a little of the energy given off is light energy; 90% of it is released as heat. This is why incandescent globes get very hot.

This is very inefficient and wastes a lot of energy.

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The globe is connected to the circuit by two metal contacts, one at the foot of the globe and the other at the side.

How do light globes work? – 2 Use the text on page 67 to complete the following.

1. What are the two types of light globes that we most often use in our homes?

2. Each globe is a sealed unit with air removed and a gas added.

What is the name of the gas?

3. Glass is a good insulator. In an incandescent globe, why do you think a glass mount is

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used?

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4. Answer as true or false.

(a) The long coiled wire of a tungsten filament provides less resistance than a short straight piece of tungsten wire. (b) Resistance causes the flow of electrons to slow.

(c) Most of the energy released by an incandescent globe is light energy.

5. Mercury has two notable characteristics. What are they?

6. (a)

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C.P ubl i cat i ons and •off o r r e vmercury i ewrelease? pur posesonl y• What type light does the

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(b) Why is the inside of a fluorescent globe coated with phosphor?

7. How does the electricity flow between the electrodes in a fluorescent globe?

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8. (a) What might cause a fluorescent globe to blow?

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(b) How is this avoided?

9. Why are fluorescent globes more energy efficient than incandescent globes?

Electricity has become so important to our lives that it is hard to imagine life without it. But electricity can be dangerous. Make a collection of signs, posters and warnings that are used to remind us of the hazards of electricity.

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Electromagnetism unplugged! north pole

Electromagnetism is a basic principle of science that has many applications for use in today’s technological world. For example, doorbells, speakers, motors and even central locking systems in cars use electromagnetism. But what is an electromagnet?

wire coil iron core

An electromagnet works just like a permanent magnet (likes repel and opposites attract), but only functions when an electric current is flowing through it.

south pole

When electrons flow along a wire between the negative and positive terminals of a battery, they generate a small, circular magnetic field around the wire. The field is strongest close to the wire and weakens further out. The effect of the magnetic field of a straight wire is increased if the wire is coiled. This can be demonstrated by the effects a current flowing through a straight wire and a coiled wire have on a compass placed close by.

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Teac he r

1. Plan your own investigations to discover more about the strength of an electromagnetic field.

Using a long iron nail as the core and staples or small paperclips, determine the effect of A the number of coils of wire on the strength of the magnetic field produced. Measure the strength of the field in paper clips.

B

Use different thicknesses of material for the core.

What effect do they have on the strength of the electromagnetic field?

Use different materials for the core; for example: aluminium, ‘lead’ from a pencil, plastic, C wood.

What effect do they have on the strength of the electromagnetic field?

Use two batteries, connected in series.

D What effect does this have on the strength of the electromagnetic field?

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between the strength of the electromagnetic field generated and:

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(a) the number of coils in the wire

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2. When you have completed your investigations, write statements to describe the relationship

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(c) the type of material the core is made from

(d) the voltage provided to run the current.

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(b) the thickness of the core

How do wind and water generate electricity?

Content focus: Inquiry skills focus:

• Useful websites: − <http://www.squidoo.com/fun-experiments2#module64854901> − http://www.internationalrivers.org/china/three-gorges-dam − <http://www.alliantenergykids.com/wcm/groups/wcm_ internet/@int/@aekids/documents/multimedia/windpower_ container.swf> − <www.need.org/needpdf/WondersofWindTeacher.pdf> − <http://sydney.edu.au/science/uniserve_science/school/ curric/k_6/energy.html>

Energy transfer in the production of electricity Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

r o e t s Bo r e p ok u S Preparation

• Discuss what students understand by the term ‘energy’ and its different forms; e.g. light, sound, electrical, mechanical. Ask: How do these compare and contrast? Discuss means of generating energy— both renewable (solar, geothermal, wind, water, tidal) and nonrenewable sources (coal, oil, natural gas). Revise electromagnetism.

(Refer to page 69.)

The lessons

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• What is a hydro-electric power plant: A reservoir is an artificial lake that is constructed where a dam can be built at one end. The dam holds the water in the reservoir and houses the equipment for converting the water power into electricity. The water in the reservoir is still and so it has potential energy. Sluice gates control and measure the flow of water from the reservoir, down the penstock (a large pipe) to a turbine. As the water falls down the penstock, its potential energy is converted to kinetic energy. The further the water has to fall, the more kinetic energy it has and the more electricity it can produce. The height the water falls is called the head. The kinetic energy from the water flowing down the penstock is transferred to the blades of the giant turbine and causes them to turn, becoming mechanical energy which is ‘doing work’. The turbine is connected to a generator in the power plant. As the turbine spins, it transfers its energy to the generator. As the generator spins, it converts its energy to electricity (using electromagnetism). The water is either pumped back into the reservoir to be used again or it continues downstream.

• Pages 71 and 72 should be used together.

Answers Page 72

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1. 1. converted 2. form 3. transferred 2. (a) (i) stored (ii) moving (b) (i) mechanical (ii) rotational (iii) electrical 3. The kinetic energy of moving water or wind, converts to mechanical energy, which turns the blades of a turbine. This gives the shaft attached to it rotational energy, causing it to spin. The spinning shaft is attached to a generator. As the magnet spins, it generates a current in the coil, which is electricity.

4. (a) A current in a wire generates a magnetic field and a moving magnetic field generates a current in a wire. (b) It is spinning and so the magnetic field around it also spins.

5. (a) A step-up transformer increases voltage; a step-down decreases voltage. (b) Step-up transformers are needed to increase the voltage, so the effect of loss of power over distance is reduced. Step-down transformers are needed to decrease the voltage to a safe level for domestic and commercial use.

Science as a Human Endeavour question Use and influence of science Teacher check

• Wind farms: Longer turbine blades have the capacity to generate more electricity as they can capture more of the wind’s energy. Wind turbines are always tall because wind is stronger higher from the ground.

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• The blades of a turbine have an air foil design. (One surface is rounded while the other is flat.) As wind moves across the rounded surface, it has to move faster to meet the wind that passes over the flat surface.

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• The major parts of a wind turbine are: − the rotor: As the wind pushes against the rotor blades, they absorb some of its kinetic energy and begin to turn. This makes the rotor hub spin with rotational energy. As the rotor spins, it transfers its energy to the shaft which begins to spin. As the shaft spins, it transfers its rotational energy to a generator − the generator: The generator converts the shaft’s rotational energy into electricity as it passes through a magnetic field. Electricity is fed into the main electricity grid through a transformer − the nacelle: This is the casing that houses the shaft and the generator where the electricity is produced − an anemometer: Located in the nacelle, this measures wind speed. The turbines turn on and off automatically, working only between speeds of 15 and 90 km/h − the tower: This supports the hub and the nacelle. It must be tall enough for the blades to clear the ground and to catch strong winds. Most towers are between 20 m and 30 m tall − the insulated cables that run down the tower and carry electricity from the generator to the transformer.

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1. Initially, the water from all holes travels a similar distance. As the carton empties and the pressure decreases, the distance the water travels from the uppermost hole also decreases.

2. As water has weight, the higher the column of water above the hole, the greater the weight; therefore, pressure forces the water out of each hole. The downward pressure is greatest on the water leaving the lowest hole and so it travels further.

By building the plant at the base of the dam, engineers are making the most of the water’s potential energy.

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How do wind and water generate electricity? – 1 We all know what water is, but what exactly is wind? Wind is created by the sun. Land absorbs heat energy from the sun and warms the air around it. As the warm air rises (because it is less dense than cool air), cool air rushes in to take its place. This fast moving air is wind.

So how can water and wind generate electricity? The answer is all about the transfer of energy. Everything has energy of some form. It can’t be created or destroyed, but it can be converted from one form to another when it is transferred between things.

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Teac he r

When water is lying still in a reservoir, it has potential (stored) energy. But when it is rushing down towards the turbines of a hydro-electric power plant, the potential energy is converted to kinetic (moving) energy. In the same way, still air has potential energy that is converted to kinetic energy when a wind develops. To turn the huge blades on a tower, wind speeds need to be at least 15km/h.

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To look at, hydro-electric power plants and wind farms are very different but the way in which they generate electricity is very similar.

When moving water or wind hits the blades of a turbine, the kinetic energy converts to mechanical energy and causes the blades to move. The turbine is attached to a shaft. As the blades turn, their mechanical energy is converted to rotational energy, causing the shaft to spin. The spinning shaft is attached to a generator, which is a magnet surrounded by copper coils.

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C.Publ i cat i ons •f orr evi ew pur posesonl y• transmission towers

step-up transformer

dam

power plant

reservoir

step-down transformer

dam wall

p ens

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generator

tock

turbine

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sluice gates

dam wall downstream outlet

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Electricity loses some of its power as it travels over a distance. To make sure it still has enough power when it reaches its destination, a step-up transformer boosts its voltage to a very high level. Huge metal towers called transmission towers support insulated cables that carry the electricity at this dangerously high voltage. Before it is connected for use, the electricity is passed through a step-down transformer, converting it to lower voltages that are safe for domestic and commercial use.

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turbine

shaft

power grid

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The principle of electromagnetism is used to generate electricity. Just as a current in a wire generates a magnetic field around itself, so a moving magnetic field generates a current.

Inside the generator, a magnet spinning inside a coil of copper wires generates a current in the coil—electricity!

How do wind and water generate electricity? – 2 Use the text on page 71 to complete the following.

1. Fill the gaps in the sentences.

1

Energy can be 3

is

2

from one

to another when it

between things.

2. (a) Write another word for each type of energy. (i) potential

r o e t s Bo r e p ok u S (ii) kinetic

(b) Kinetic energy comes in many forms. Rearrange the letters to find three of them.

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(i) a a c c e h i l m n (ii) a a i l n o o r t t (iii) a c c e e i l l r t

3. Describe how the energy in moving water or wind is converted to electricity.

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4. (a)

© R. I .

C.Publ i cat i ons •f orr evi ew pur posesonl y• What is the two-way relationship between current and magnetic field?

(b) In what way is the magnet in a generator moving and how does its magnetic field move?

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5. (a) What is the difference between step-up and step-down transformers?

Physical sciences

(b) Why are transformers needed?

People in different parts of the world have access to a variety of sources of energy that can be used to generate electricity. Discover the main ways in which Australia and other countries across the world generate electricity. Are we doing enough to reduce the use of fossil fuels?

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Making the most of water power Hydro-electric power plants are built at the base of dams where the water is forced onto the blades of turbines.

In this investigation, you will discover why they are not built at the top of a dam.

You will need: â&#x20AC;˘ 1 empty 1-litre milk/juice carton â&#x20AC;˘ masking tape What to do:

â&#x20AC;˘ 1 large nail

r o e t s Bo r e í˘ľ p ok u S

í˘ą Use a nail to make holes in the carton at

Observe and record how the water empties through each hole and how it changes as the water level falls.

í˘˛ Tape over all holes with one length of

í˘ś Tape all the holes individually.

masking tape.

í˘ł Draw a line at the top of the carton. Fill the

í˘ˇ Refill the carton. Untape one hole and measure the distance between the edge of the sink and where the water lands.

Re-tape the hole.

carton with water to this level.

í˘´ Hold the carton firmly at the edge of a kitchen sink and rip away the strip of tape.

í˘¸ Repeat Step 7 for the remaining holes.

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C.Publ i cat i ons Untaping allo holes ate once â&#x20AC;˘f rr vi ew pur posesonl yâ&#x20AC;˘

Results: 1.

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2-cm intervals, as shown in the diagram.

All holes must be the same size.

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1. @ 2 cm 2. @ 4 cm 3. @ 6 cm

Observation

Distance (cm)

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4. @ 8 cm Conclusion:

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2. Untaping one hole at a time Hole

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How does the water empty through each hole and how does this change as the water level falls?

How do we get power from the sun?

Content focus: Inquiry skills focus:

• Discuss the financial and environmental cost of using electrical appliances, the cost and savings of installing and using solar energy, and applications that use solar power; for example: calculators, swimming pool heaters, emergency telephones, domestic hot water systems. Ask: What are the advantages and disadvantages of solar energy? (For example: cost of installation, storage, aesthetic appeal of rooftop panels, reduction of fuel bills, clean, sustainable.)

Harnessing power from the sun Planning and conducting Processing and analysing data and information Evaluating Communicating

Answers

r o e t s Bo r e p ok u S Page 76

Background information

1. (a) No, because solar power can only be generated by the light of the sun. (b) There are less hours of daylight and a greater chance of cloud cover, which reduces the rate of electricity production. (c) (i) voltaic (ii) photo 2. (a) Electricity is generated immediately. (b) 1. sunny 2. cloudy 3. (a) the amount of electricity being generated at a given moment (b) the amount of electricity being generated over time/the total amount of solar energy produced by the solar panels 4. The inverter converts the direct current electricity that is made into the alternate current electricity that we use in our homes.

5. (a) Excess electricity produced would be transported to the main electricity grid. (b) The solar panels would not produce enough electricity to satisfy the demand and the shortfall would be supplied by the main electricity grid.

Science as a Human Endeavour question Nature and development of science/Use and influence of science Students may wish to compare lists and add to them. Revise the structure and language features of an exposition before the students write their own.

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• The amount of energy provided by the sun is vast. It is there to be used now and forever. The effectiveness of solar energy-harnessing technology is progressing rapidly and many people are turning to solar energy to power their homes.

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• Advantages of solar power: − Solar energy generation produces little pollution. − The cost of installation is usually covered by reduced fuel bills in first few years. − Solar power is completely renewable. − Remote locations can have access to solar power. − Solar power battery chargers can store solar energy generated.

• Disadvantages of solar power: − Initial cost of installation is high. − A large area is required for panels. − Pollution and clouds can reduce the efficiency of the photovoltaic cells. − Solar energy can not be generated at night. − The location of solar panels is critical. Anything that obstructs the sun’s rays will reduce the efficiency of the system.

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• Useful websites: − <http://www.youtube.com/watch?v=qYeynLy6pj8> − <http://www.eia.doe.gov/kids/energy.cfm?page=solar_homebasics> − <http://www.kidcyber.com.au/topics/solar.htm> − <http://encyclopedia.kids.net.au/page/so/Solar_power> Preparation

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1. Teacher check 2. (a) Generates electricity from sunlight. (b) Stores electricity generated by the solar cells; powers the controller board. (c) Keeps electricity generated by the solar cells flowing in one direction, towards the battery. (d) Turns on the LED. (e) Detects darkness and sends this information to the controller board. (f) Gives out light.

3. Teacher check 4. Examples may include electronic charger docks for mobile phones, MP3 players, battery chargers, roadside assistance telephones, ceiling fans.

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• Draw a large flow chart showing how solar energy is converted to electricity suitable for use in the home.

Physical sciences

• Provide a number of solar-powered garden lights for students to dismantle and rebuild. Sets are available cheaply from large hardware stores.

The lessons • Pages 75 and 76 should be used together.

• Discuss how electricity has improved the ease with which household chores can be done and how domestic life is more comfortable; e.g. dishwashers, irons, washing machines, electric fans, air conditioners, electric fires.

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Light energy from the sun is collected in solar panels. Each panel contains a number of special cells called photovoltaic (PV) cells.

Solar panels are always located where they will receive the maximum amount of sunlight.

Power is harnessed from the light of the sun, not from the heat.

As such, the cells work well in winter even when the heat is less intense.

Less electricity is produced by solar panels in winter because there are fewer hours of daylight and there is more chance of cloudy skies, which reduce the intensity of the sun’s rays.

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75 ammeter

A

inverter

(DC) to 240 volts

AUSTRALIAN CURRICULUM SCIENCE

Physical sciences

The electricity passes through the cells in each solar panel and then among the panels, along insulated cables, into an ammeter. This measures the magnitude (amount) of an electric current at any given moment.

If a dark cloud hides the sun for a short while, the reading on the meter drops and then rises again when the cloud moves away.

As sunlight strikes a solar panel, some of its energy is transferred to each PV cell. The construction of the cells allows them to instantly convert the light energy into electricity.

This is called the photovoltaic effect, which means ‘electricity from light’.

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The output of power from solar panels is measured in sun hours. One sun hour is equivalent to the amount of power that would be generated in one hour of strong midday sun.

On a cloudy day, it may take a few hours for a panel to produce one sun hour of power.

solar panels

© R. I .

C.Publ i cat i ons •f orr evi ew pur posesonl y• kW/h meter

television

iron

main switchboard

toaster

main electricity grid

cooker

The kilowatt per hour meter records the total amount of solar energy produced by the solar panels.

The electricity passes through the main switchboard, which supplies the energy for all household appliances.

When the solar panels produce more electricity than is needed, the excess is transported to the main electricity grid.

When the solar panels do not produce enough electricity for all appliances being used, electricity is supplied by the main electricity grid.

The type of electricity produced by PV cells is called direct current (DC). The type we use in our homes is called alternating current (AC).

An inverter transforms the electrical current from the solar panels into the type needed for electrical appliances in the home, such as lighting, cookers, computers and televisions.

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How does solar power work?

Solar power is a reliable source of sustainable energy generated from the light of the sun. It requires no fossil fuels, produces no noise and little pollution, and once installed, it requires no maintenance.

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How do we get power from the sun? – 1

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r o e t s Bo r e p ok u S

How do we get power from the sun? – 2 Use the text on page 75 to complete the following.

1. (a) Can solar power be generated 24 hours a day? Explain your answer.

(b) Less electricity is produced by photovoltaic (PV) cells in winter because …

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(i) electricity?

(ii) light?

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(c) Which part of the word photovoltaic means:

2. (a) How long does it take for the PV cells in a solar panel to generate electricity?

(b) More sun hours would be produced by a solar panel on a 2

day than on a

day.

© R. I .

C.Publ i cat i ons •f orr evi ew pur posesonl y• A kilowatt per hour meter measures

3. (a) An ammeter measures

(b)

1

.

.

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4. What is the purpose of an inverter?

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5. (a) If a family went on holiday for a month during the summer, what would happen to the electricity generated by the PV cells in the solar panel on their roof?

Physical sciences

(b) If a family had lots of visitors for a month during the winter and the weather was so bad they spent most of their time at home, how would this affect their electricity supply?

A single power cut at home can make you realise just how reliant we all are on electricity. Make a list of all the electrical devices in your home that are powered by mains electricity. Imagine that multiplied by all the homes in the world!

Write an exposition to encourage people to install solar panels in an effort to reduce their use of energy derived from fossil fuels.

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Solar-powered pathways Solar-powered garden lights are a simple application for using solar cells.

Most solar-powered garden lights use an array of four solar cells which generate enough electricity during the day to provide a safe illuminated pathway at night.

1. Examine the construction of the solar-powered garden light as you dismantle it into its component parts. solar-powered garden lights

r o e t s Bo r e p ok u S

Power from the battery runs the controller board, which is connected to a photoresistor. At night, when the photoresistor detects darkness, it sends the information to the controller board which turns on the LED (light-emitting diode).

glass cover

solar cells

photoresistor

controller board

battery

LED globe

lamp cover

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The solar cells connect directly to a battery through a diode. The battery stores the electricity generated during the day and discharges it at night. The diode keeps the electricity flowing in one direction towards the battery. A fully charged battery can run for about 15 hours, providing illumination equivalent to 50% of candle light.

2. Describe the role of each component in a solar-powered garden light.

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C.Publ i ca t i ons Role (a) Solar cells •f orr evi ew pur posesonl y• Component

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(c) Diode

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(d) Controller board (e) Photoresistor (f) LED

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3. On A4 paper, draw a diagram of the components of a solar-powered garden light. Label each component and include your description of its role.

4. List other applications of solar power.

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(b) Battery

Which energy sources for the future?

Science as a human endeavour unit: Content focus: Inquiry skills focus:

The lessons • Pages 79 and 80 should be used together.

Use and influence of science

• Discuss the rates of formation and mining of fossil fuels: Having taken millions of years to form, fossil fuels are nonrenewable but are being used at an increasing rate. Also discuss how the use of fossil fuels has a negative effect on the environment, and how this, along with rising usage cost, is making people and companies seek alternative energy sources. Discuss the possibility of using sustainable energy sources for all electricity production so that unsustainable sources might be conserved. Discuss the different by-products of oil: How important are they in today’s society? Could alternative sources be used in their manufacture? Discuss the advantages and disadvantages of sustainable and unsustainable energy sources.

The rise and fall of unsustainable sources of energy Planning and conducting Processing and analysing data and information Evaluating Communicating

• On page 81, students research the use of geothermal energy in New Zealand. The questions are a guide to their research. Diagrams will help clarify their text.

• A primary source of energy is one that is found in nature. It can be sustainable or unsustainable; for example: wind, water, coal and oil.

A secondary source of energy is one that is generated by a primary source; for example, electricity is generated when coal is used to heat water which produces steam which drives a turbine, or when falling water is used to drive a turbine. The turbine, then spins a shaft which is connected to a generator which produces electricity.

Answers Page 80

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Background information

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1. (a) sustainable, unsustainable (b) Sustainable energy sources will always be available. Some unsustainable energy sources are formed from the remains of plants and animals that died millions of years ago. As they are used, they are not replaced. (c) sustainable energy sources: sun, wind, water, tides, geothermal heat; unsustainable energy sources: coal, oil, natural gas 2. Across: 3. Spills on roads and waterways, damaging wildlife. 4. Loss of layer protecting Earth from damaging sunrays. 5. May trap heat within the Earth’s atmosphere.

Down: 1. Waste from fossil fuel combustion, which seeps into soil and waterways and damages ecosystems. 2. Waste from fossil fuel combustion, which combines with water vapour in the air to create a damaging rain.

3. Teacher check. Expect the answer ‘No’. Different places are more suited to using different energy sources; for example, wind energy is more suited to windy areas like coastlines and mountains, geothermal energy is most suitable in areas with high volcanic activity.

• Electricity is the main source of power in the world today. It is popular because it is usually reliable and is relatively clean and easy to use.

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• Useful websites: − <http://www.olliesworld.com/planet/aus/info/issue/energy.htm> − <http://www.eia.doe.gov/kids/energy.cfm?page=coal_homebasics> − <http://www.alternate-energy-sources.com/facts-about-solarenergy.html> Preparation

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Teacher check. Websites such as <http://www.teara.govt.nz/en/ geothermal-energy/3> may be useful to the students

• Collect pictures of environmental scenes, damaged by pollution related to fossil fuels.

Physical sciences AUSTRALIAN CURRICULUM SCIENCE

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• Generating electricity from unsustainable fossil fuels creates pollution. Because it is a secondary source of energy, electricity can be generated from other, more sustainable, sources which have a less detrimental effect on the environment. It is necessary for these sources to be developed and exploited as the use of fossil fuels is becoming a non-viable choice in terms of availability as well as pollution.

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Which energy sources for the future? – 1 Electricity is needed to power electrical appliances, machinery and different forms of transport. The source of energy has to come from somewhere and it can be either sustainable or unsustainable.

Sustainable sources of energy will not run out. They are available for this generation and for all generations that follow. Examples of sustainable energy sources are the sun (solar energy), wind, water, tides and the heat from the earth’s core (geothermal energy). Producing electricity this way creates relatively little pollution.

Unsustainable sources of energy are those produced by fossil fuels; coal, oil and natural gas that formed millions of years ago from the remains of dead plants and animals. They are unsustainable because once they are used up, they can not be replaced. We now know that burning fossil fuels to generate electricity creates environmental problems that damage the health of the planet; for example:

r o e t s Bo r e p ok u S

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Toxic waste: Toxic waste from fossil fuel combustion can seep into soil and water, damaging plant and animal life and destroying ecosystems.

Acid rain: Burning fossil fuels releases damaging gases that rise into the atmosphere, and can combine with water vapour and fall as acid rain. Acid rain damages plant and animal life, and the soil, inhibiting crop growth.

© R. I .

C.Publ i cat i ons Greenhouse gases: The gases released from fossil fuels •f rr e vi ew ur posesonl y• have the effect ofo trapping heat within the p Earth’s atmosphere.

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This may cause global warming and changes to the climate. If changes to climate do occur, rainfall may decline and average temperatures may rise.

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Oil slicks: Transport accidents involving liquid fossil fuels have caused environmental disasters; for example, oil slicks from damaged oil tankers have spread across beach and ocean, destroying local habitats and wildlife.

Access to sustainable sources of energy varies across the globe.

• Regions with high volcanic activity can make use of geothermal energy.

• High altitude areas or those with exposed coastlines favour wind energy.

• Areas in the tropics where the hours of daylight are relatively constant throughout the year, could effectively utilise solar power.

We need electricity but we don’t need to burn fossil fuels to produce it. Renewable energy sources can be used to generate electricity with minimal impact on the environment.

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Ozone layer depletion: The Earth is protected from certain types of harmful sunrays by the ozone layer, which works like a protective blanket within the atmosphere. The build up of certain manufactured gases has depleted the strength of the ozone layer and allows greater amounts of types of harmful solar rays to reach the Earth’s surface.

Which energy sources for the future? – 2 Use the text on page 79 to complete the following.

1. (a) What are the two types of energy sources? and (b) What is the difference between them?

r o e t s Bo r e p ok u S

2. Write clues for the

1.

answers to the puzzle.

3.

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(c) Give two examples of each type of energy source.

2.

T O

I

L

S

L

I

C K

A

C

X

I

I D © R. I .

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P u b l i c a t i o n s C R Ay• •f orr evi eWw pur posesonl 4.

O Z O N E

L

A Y E R D E P

L

E

T

N

T

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5.

G R E E N H O U S E G A S E S

Across

3.

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5.

O N

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S

I

Down

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2.

3. Do you think all parts of the world can rely on all forms of sustainable energy sources? Give reasons and examples to support your answer.

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Sustainable energy sources on tap Across the globe certain types of sustainable energy sources are more accessible than others. It makes sense for a region to make the most of whichever source is most easily available. For example, in tropical areas with consistent hours of sunlight throughout the year, solar power might be most effective. In high altitude or coastal areas that experience strong winds, wind power might be the best option.

In areas with high volcanic activity, geothermal energy is an obvious choice.

You are going to research geothermal energy and its uses in New Zealand, a country with high volcanic activity.

r o e t s Bo r e p ok u S

Use the table as a framework. Write notes to answer the questions before preparing a written presentation. Include diagrams in your presentation.

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Use of geothermal energy in New Zealand

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What does the term ‘geothermal energy’ mean and from where does it come?

Why is geothermal energy sustainable?

© R. I .

C.Publ i cat i ons How is the energy from • f orr evi ew pur posesonl y• geothermal reservoirs

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How is the energy from geothermal reservoirs harnessed for electricity generation?

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What are the advantages of geothermal energy?

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How is the energy from geothermal reservoirs harnessed for heat pumps?

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harnessed for direct use?