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Contents Topic 1 Humans and animals


Animal skeletons Your skeleton Growing bones Functions of the skeleton Protecting your organs Muscles Moving your bones Investigate moving bones Drugs and medicines Different medicines

2 4 6 8 10 12 14 16 18 20

Looking back Topic 1


1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10

Topic 2 Living things in their environment 2.1 2.2 2.3 2.4 2.5 2.6 2.7

The importance of the environment Adapting to different habitats Investigating different habitats Identifying and grouping animals Using identification keys Human activity and the environment Waste and recycling

24 26 28 30 32 34 36

Looking back Topic 2


Topic 3 States of matter 3.1 States of matter 3.2 Water 3.3 Heating matter

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39 40 42 44

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3.4 Cooling matter 3.5 Liquid to gas 3.6 Gas to liquid Looking back Topic 3

Topic 4 Sound 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

46 48 50 52


How sounds are made Measuring sound Sound travels through different materials Reducing sound levels Soundproofing materials Musical instruments Pitch Changing the pitch of a musical instrument

54 56 58 60 62 64 66 68

Looking back Topic 4


Topic 5 Electricity and magnetism


Electrical circuits Building circuits Why won’t it work? Electrical current Magnets Investigate magnetic forces Magnets and metals Using magnets to sort metals

72 74 76 78 80 82 84 86

Looking back Topic 5


5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8


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Humans and animals

In this topic you will learn more about the structure of the human body. You will learn that humans and some animals have bony skeletons inside their bodies. Then you will find out more about the functions of your own skeleton. Next, you will look at how muscles work in pairs to allow us to move our skeletons. Last, you will find out about medicines that we can take when there is something wrong with our bodies. 1

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Key words

• bones • internal • skeleton • move • support

1.1 Animal skeletons Look at this photograph of a jellyfish. Jellyfish have soft floppy bodies with no bones. 1 Can you think of any other animals with soft bodies and no bones? 2 Some insects, such as locusts and beetles, have hard bodies. Do you think they have bones? Some animals do have bones inside their bodies. These bones are joined together to form an internal skeleton. The skeleton helps the animal move and supports it, as well as protecting the soft parts inside its body.


Look at the skeletons of a frog, bird, fish and snake in the photographs.




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Humans and animals



Hold one arm out in front of you. Feel your wrist with your other hand. 3 What do you feel? 4 Why isn’t your arm soft and floppy? 5 What does this tell you about your own body structure?

Activities 1 Make a table of

animals with no skeleton and animals with an internal skeleton. Try to find at least five examples of animals in each group.

2 Some animals have a hard covering

on the outside of their body. This is called an external skeleton or exoskeleton. Make a list of at least five animals with an exoskeleton.

3 What is an X-ray photograph? What are these used for in modern medicine?

I have learned ●

Some animals and human beings have bones inside their bodies.

The bones are joined together to form an internal skeleton. 3

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Key words

1.2 Your skeleton Like some animals, human beings also have a bony skeleton inside their bodies.

• skeleton • joints • spine

When you squeeze your arm you can feel the bones inside it. Bones are hard and strong and they form a rigid frame inside your body. This frame of bones is called a skeleton. Your skeleton helps you to move and supports yyour body, y, as well as protecting the soft parts inside yourr body. 1 Do you know the names of any of the bones in your body? Show them to your partner and say their names. There are 206 bones in a human skeleton. On their own, bones are hard and stiff and they cannot bend. However, the bones in our skeletons are connected to each other at joints. Because joints are flexible, we are able to bend and move our bodies. 2 Find three joints on the skeleton. In what way does each joint allow you to move your body?

skull jawbone shoulder blade should ribs elbow spine (backbone) hip bone forearm

thigh bone kneecap shinbone


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Bones in museums and the bones of dead animals in the environment are dry and they crumble easily. Living bones are not dry and are very strong.


Humans and animals

Activities 1 Describe some

differences between the bones that make up the human skeleton.

2 Find out what

happens when you break (fracture) a bone. What is the difference between a complete fracture, a greenstick fracture and an open fracture?

3 When you break a

bone you may have to wear a splint or a cast. Make a poster to teach young children what they can expect if they have to wear a splint or a cast.

I have learned ●

Humans have bony skeletons inside their bodies.

Skeletons are made of different kinds of bones connected to each other at joints. 5

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Key words

1.3 Growing bones When you were a baby, you were much smaller than you are now. Your skeleton was also smaller. Our skeletons grow as we grow.

• X-ray • bones • cartilage • calcium

Compare these X-ray images of human hands. 1 year old

3 years old

13 years old

20 years old

1 What differences can you see between the hands in the photographs? 2 Describe what you think your hand would look like on an X-ray. 3 What do you think happens to the bones and joints in the hand after 20 years of age? 6

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As we grow from babies to adults our bodies, including our bones, get bigger. When a baby is born, it has more than 270 bones. Some of a baby’s bones are made from a soft, flexible material called cartilage. As the baby grows, the cartilage grows too. Over time the cartilage is replaced by bone. This is why calcium is very important for young children – they need it to build healthy bones. 4 Your outer ear and nose are made of cartilage. Feel your ear and nose. Compare the cartilage in your ear with the bones in your hand. As a baby grows, some bones grow together (fuse) to form the 206 bones in an adult skeleton. Between the ages of 20 and 25, your bones stop growing and your skeleton no longer increases in size as you get older.


Humans and animals

Activities 1 Do taller people have

bigger bones than shorter people? Work in groups of three or four. Use a tape measure to measure each person’s height, arm length, leg length and head circumference. Record the measurements in the table on Workbook page 5.

2 Draw four separate

graphs to compare the measurements. What do your results suggest?

3 If you took the same

measurements using the same people in five years’ time, would you get the same results? Explain your answer.

I have learned ●

Bones are alive and they grow and change as we grow and change. Our skeleton grows with us.

By the age of 20 to 25, our skeleton has grown to full size and it no longer grows. 7

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Key words

1.4 Functions of the skeleton Without your skeleton you would not be able to stand, walk or run. Your body would be soft and shapeless. Your skeleton allows you to stand upright and to move. It also supports your body and protects your soft organs. 1 Put your hand on the back of your neck. Can you feel the bones joining your head to your body? Now run your fingers downwards. Try to feel the bumps along your backbone.

• support • protect • organs • backbone

vertebrae ve

Your backbone, or spine, is important for supporting your body. It also allows you to twist and bend. 2 What do you think the discs of cartilage do? discs of rubbery cartilage e


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Humans and animals

Activities 1 Make a model of a

thigh bone. Decide how you will make it light but strong, like a real bone. Use Workbook pages 7 and 8 to record your work.

Your backbone is a column of small, ring-shaped bones called vertebrae (vert-eh-bray). A single one of these bones is called a vertebra. The vertebrae are separated by small cushions of rubbery cartilage. The cartilage stops the vertebrae from rubbing together and acts like a shock absorber to cushion the vertebrae from jolts when you walk and run. Your backbone also protects the nerves that send messages from your brain to the rest of your body. Your legs are important for support too. The leg bones are large and strong. The bone in your thigh is the largest bone in your body.

2 What can you do to

test the strength of the model bones? Work with another group to test the model bones. Whose bone was stronger?

3 The backbone is

different from the thigh bone. Think about how you could build a model to show the backbone and the way it allows the body to move. Draw a labelled diagram of your proposed model.

I have learned ●

The skeleton allows us to move.

It also supports our body and protects our organs.


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International Primary Science Student Book 4  

International Primary Science Student Book 4  

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