How It Works Book of Amazing Homeschooling Projects

BOOK OF

AMAZING N I G L O O H C S HOME PROJECTS ONE CHARGE A PH NS O M LE H WIT

WATCH OSMOSIS IN ACTION

TEST FOR ACID

GO STARWATCHING

EXTRACT YOUR DNA

MAKE OUR OWN COY MPOST

ER MAKE WATIT Y AV DEFY GR

BOOK OF

AMAZING HOMESCHOOLING PROJECTS

T

he cool projects and experiments you can perform in your own home, with just a few ordinary household items or ingredients, will

blow your mind. In this book we’ll show you how you can do anything from making hot ice, to turning a lemon into a battery, to crafting your own pinhole

camera, and even how to extract your own DNA. You can go without the chemistry lab and the design & technology workshop for a while, all you need is the know-how and step-by-step instructions in each of the projects inside, to pull off some truly amazing feats of science. We guarantee you’re going to have a lot of fun (and learn something at the same time) with what we’ve got in store for you!

Ben Biggs Editor

S T N E T N O C 06 Make a zoetrope Re-create a Victorian novelty toy with just a few household objects

08 Lemon battery experiment Learn about how batteries work by powering an LED light with some lemons

10 Make hot ice his supercool liquid instantly freezes at T room temperature

A few steps to help you get to grips with looking at the stars

19 Create recycled paper

31 Bubbles inside bubbles

Take your unwanted mail and turn it into original handmade paper

Create an incredible double bubble using the science of hydrogen bonds

19 Make invisible ink

31 Clean tarnished silver

20 Red cabbage litmus paper

See for yourself how and why water moves between different places

13 Grow beans in cotton wool Learn about root formation with a bean and some cotton wool

13 Fit an egg into a bottle Amaze everyone with this clever magic trick that’s all about air pressure

14 Build a lung Turn everyday household items into a working lung model

15 A DIY chromatography test Find out how to separate inks into their different coloured components

15 Learn about sound waves simple experiment to show how sound A travels and why it changes its pitch

16 Make a spectrometer Split light into its constituent colours and learn about atoms with this easy-to-make gadget used by NASA scientists

earn how to return your tarnished silver to L its former gleaming glory

32 Cartesian diver experiment

Try this cheap and easy way of testing whether a substance is an acid or a base

Explore the principles of buoyancy, density and pressure with this easy experiment

22 Extract your own DNA

34 Anti-gravity water

Collect a sample of DNA from your cheek cells with this great home experiment

How water breaks free of gravity to rise inside a glass

23 Make sugar crystals

36 Exploding colour

Study the formation of crystals and make a tasty treat!

We combine food colouring, milk and soap to produce colourful results

23 A model heart chamber

38 The double-slit experiment

See how the amazing muscles in your heart keep blood pumping around your body

Understand the basics of wave-particle duality with this simple home experiment

24 An electromagnet

40 Split water

We show you how to build and experiment with homemade electromagnets

Conduct an electrolysis experiment to split water into hydrogen and oxygen

26 Penny drop experiment

41 Make your own compost

Explore Isaac Newton’s first law of motion with some simple items

urn your vegetable and garden waste into T nutritious plant food

28 Non-Newtonian fluid

42 The perfect paper plane

It’s a liquid, Jim, but not as we know it… the harder you push it, the more solid it is

6

30 Use a telescope

Turn an empty Pringles tube into a working, old-fashioned-style camera

Learn how to write secret messages that can be revealed by the power of heat

12 Watch osmosis in action

04

18 Make a pinhole camera

Some after-school crafting fun. Can you beat the world paper plane-flying record?

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34

10 12

22

15 41

20

36

05

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

MAKE A ZOETRO Re-create a Victorian novelty toy with just a few household objects

Before the advent of motion pictures, animated characters – be they real or not – were confined to simple and novel toys, or oldfashioned shadow plays. One of these playthings was the zoetrope – invented in its modern incarnation by British mathematician William George Horner in 1834 – which created an illusion of movement from the rapid spinning of static pictures. It became an overnight success and by the 1860s they were common to the houses of the wealthy and privileged. Luckily, today a DIY zoetrope can be constructed with little to no cost at all, with just a small selection of household items needed to relive the days of yore. Try it out – they are remarkably fun little gadgets.

Step 1. Okay, to start you need to take your white paper strip and wrap it around the inner lip of one of the upturned coffee can lids. If it’s too long, mark the point where the ends meet and trim off the excess. Next you have to take a measurement of the length and divide it equally by 12 segments using your ruler and pencil.

ST EP 1

ST EP 2

Step 2. Now draw (or print off) a horse running, with each segment moving its position onwards. Importantly though, ensure that whatever action you draw ends up full circle by segment 12, as this way the zoetrope’s animation will play out on loop, with no break in the action.

ST EP 3

Equipment: 1 x A 3 white paper (cut into a long strip) 1 x A 3 black card (cut into a long strip) 2 x Coffee can lids 1 x Pencil 1 x Craft knife Some liquid glue 1 x Ruler 1 x Scissors 06

Step 3. The next thing to do is take your strip of black card and cut it down so it has the same length of your paper, but twice the width (ie the height). You can do this easily by just placing the white paper over the card and marking it with a pencil. Once this is done divide the top part of your black card as you did with the white paper, with small pencil dashes to mark out each segment transition. Extend the lines from the halfway point to the top as shown.

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ST EP 4

Step 5. With great care, take the craft knife and score an X-shape puncture in the centre of the coffee can lid. Don’t make this any larger than a centimetre. Once done try inserting your pencil through the slit. It should fit through and then get snagged on the metallic rubber holder on the end. If the pencil is a little wobbly by step 7 you can always apply some glue or Blu-Tack to secure it.

Step 4. Now, with your scissors, cut either side of each pencil line on the top of the card down to the halfway line so that you are left with 5mm (0.2in) gaps at each segment transition. These only need to be small so take your time. If you’ve completed this step-by-step correctly up to this point you should have something like this. Now put it to one side.

Step 6. Now to assemble the zoetrope. Draw your pencil back out of the slit in the lid and place it to one side. Place the lid upside down on a level surface and squirt a thin line of glue around its inside rim. Pick up your black card strip and glue it in place, ensuring that the slatted windows are at the top and the solid base at the bottom. If you do this correctly you should be left with a crown-like structure as shown here.

ST EP 6

ST EP 7

Step 7. Finally, take your paper strip and insert it into the base of the structure, ensuring the horses face outwards and that both ends meet without any crossover. Once satisfied with the fit, glue this in. Now place the second can lid on top and reinsert your pencil as before and grip it between the palms of your hands. Rub your hands back and forth to rotate the pencil and the entire zoetrope, while viewing the horses through the slatted windows. Amazingly the horses are now one that appears to be galloping. Congratulations, you have just built your very own zoetrope!

07

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC Learn about how batteries work by powering an LED light with some lemons Batteries are now an integral part of modern society. They work by encasing a positively charged electrode (cathode) and negatively charged electrode (anode) within an electrolyte solution that, when completed in a circuit via a load (an electrical appliance), cause the cathode to experience an oxidation reaction. This involves multiple ions from the electrolyte solution combining with the cathode, which produces a compound and releases one or more electrons.

These electrons are then absorbed by the anode, producing electricity.

This may sound complicated, but the same reaction can be achieved with lemons. A lemon’s acidic content acts in the same way as an electrolyte solution. As such, when a positive and negative electrode are inserted into it (for example, a copper penny and galvanised nail), the lemon’s electrically conducting insides ­initialise the same oxidising process, freeing electrons and generating a little electricity.

Due to the impurities of both the electrodes (pennies commonly are not 100 per cent copper) as well as the relatively weak acidity of the lemon, only a small amount of electrical potential difference can be generated. However, by combining four lemons you can produce a multi-cell battery that is capable of powering a small LED.

Equipment: 1 x multimeter 4 x lemons (fresh) 4 x copper pennies 4 x galvanised nails 5 x crocodile clips Some copper wire 1 x LED 08

Lemon batte ST EP 1

A

B

Step 1. First, take a lemon and insert both a copper coin and galvanised nail into its top left and right as depicted here. Ensure that both items penetrate the skin as deeply as possible, while retaining a graspable surface area above the surface. In addition, ensure that the coin and nail do not come into contact within the lemon. When this is achieved, repeat the process on each of the remaining lemons.

Step 2. When all four lemons are prepared, line them up in a row. Next, taking three crocodile clipped copper wires, connect each of the lemons to the next from coin to nail. If you have connected them properly you should have something like this. It is important that the wires run from coin to nail, as that way the lemons’ produced power will accumulate to LEDpowering levels.

B

ST EP 2

A

Sto p! Sc ien ce tim e!

This is a good time to review the scientific principles of the experiment Both the objects stuck into each lemon are acting as electrodes, with the coins serving as positive electrodes and the nails as the negative electrodes. As such, when the nails are oxidised inside the lemons electrons are released.

The energy contained within these electrons is what powers the LED, flowing to each lemon’s negative electrode via their acidic internal solutions. By connecting the lemons with copper wire, that energy is accumulated over each lemon and transferred to the LED.

LEMON BATTERY EXPERIMENT

ery experiment Step 4. Okay, provided you have a reading around 3.50 volts it’s now time to connect the LED light to your lemon battery.

Disconnect your multimeter if you have used one and connect the free clips to the LED’s plus and minus pins. You can determine which is the minus pin by the indent on the side of LED’s plastic casing. Remember as well that the crocodile clip leading from the furthest right-hand coin must connect to the minus pin on the LED, and the plus pin on the LED to the furthest left-hand nail.

© jbru so

ST EP 3

ST EP 4

A

B

Step 3. If you have a multimeter, now is a good time to utilise it.

First, attach the remaining two wires to the remaining unclamped nail and coin located at either end of the lemon lineup.

Once this is achieved connect the free ends to the multimeter and take a reading. If you have set up the experiment correctly, the multimeter should give a reading of approximately 3.50 volts.

Step 5. Upon completing the circuit the LED should light up, powered purely by the lemons’ oxidising effects. If this is the case congratulations, you have created your very own multi-cell lemon battery. Why stop here, however, why not try some variables on the experiment too in order to generate a larger electrochemical reaction? For example, does using a larger nail and penny make a difference to the LED’s luminosity? Does switching the lemons for potatoes have any effect?

ST EP 5

A

Co nc lus ion

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So what have we learned here? Batteries, in their simplest form, consist of an anode, cathode and electrically conductive electrolyte solution.

Further, their energy comes from an electrochemical oxidation/ reduction process instigated when the battery cell is connected in a circuit to a load. Finally, while everyday batteries such as those found in your television’s remote control are made from pure substances (100 per cent pure metals/salt-based electrolyte pastes), the same electrochemical cells can be crudely replicated using impure substances, such as copper coins, nails and lemons.

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G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

DISCLAIM ER

This experi ment shou ld only be perfor supervisiomed under adult n . The saucep liquid will an an care must be very hot and extr d be ta em form of ho ken. Also, while th e should not t ice is non-toxic, it is be do not cove consumed. Final still boilin r your liquid when itly, g, cause the coas the pressure mayis ntainer to explode.

Make hot ice With this experiment, we will show that a substance could be created that was a liquid at room temperature but, when it was disturbed, would immediately crystallise and form what is known as hot ice.

Hot ice is an amazingly cool substance and the ingredients required are easy to obtain. However, it is difficult to make, and you probably won’t get it right on your first attempt, but don’t give up hope. You can either re-melt any failed hot ice or start again, making sure to follow the method carefully.

This is a great experiment to do at home and an even better one to do at school. You can directly see the effects of crystallisation and there’s plenty of science embedded into the fun of seeing hot ice in action. If you do replicate our experiment, make sure you send us some photos so we can see how it went.

This supercool liquid instantly freezes at room temperature ST EP 1

Step 1. First, a litre of clear store-bought vinegar must be measured out. This must be clear, as brown vinegar contains impurities that will prevent the experiment from working. Next, you need to add about three to four tablespoons of baking soda (sodium bicarbonate) to the vinegar. This has to be done slowly, as the reaction can make the liquid explode over the side of the container. Stir this until all the baking soda is dissolved and then put the mixture on to the hob to boil.

Step 2. You need to get rid of about 90% of the liquid, so leave it to boil for over 30 minutes. You’ll start to notice a white substance on the side of the pan. This is sodium acetate, and a bit of this needs to be saved for later use. Eventually, a crust (sodium acetate anhydrous) will begin to form on the liquid.

At this point, take it off the boil and transfer it into a container. This must be immediately covered to prevent the substance crystallising. You then need to cool it, so place it in an ice bath for 15 minutes or a fridge for a bit longer.

ST EP 2

A

Equipment: 1 x litre of clear vinegar 4 x tablespoons of baking soda 1 x Steel saucepan 1 x Plastic container

10

B

MAKE HOT ICE ST EP 4

ST EP 3

A

Step 4. The points where sodium acetate is introduced will begin to crystallise. After a few seconds the entire liquid will appear to freeze.

However, when touched, the substance is hot and not cold because the process of crystallisation here is exothermic, so heat is given off as the liquid solidifies. So, what’s happened in this experiment?

Step 3. The liquid needs to cool below room temperature. This makes it into a supercool liquid that will exhibit the characteristics of hot ice. Once it’s cooled, you can take the lid off and put some of the white sodium acetate collected earlier in the liquid.

B

Hot ice equation –

Na [HCO3] +

+ CH –COOH 3

Baking soda

Vinegar

–

CH3–COO Na

+

+

Sodium acetate

H2O + CO2 Water

Carbon dioxide

Conclusion . Almost every substance has a freezing point, but for something to solidify the molecules must rearrange from a liquid to a solid or crystal arrangement. However, hot ice, or sodium acetate trihydrate, is a supercool liquid where the molecules do not rearrange until they are disturbed, in this case by introducing sodium acetate. Hot ice melts at 58 degrees Celsius and is a crystalline solid at room temperature, allowing this effect to be produced as the baking soda and vinegar are heated. The unarranged molecular structure results in the occurrence of this crystallisation effect. You can re-use your hot ice by adding vinegar until the solid crystals are fully dissolved and repeating our method again.

Co nc lus ion

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G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

Watch osmosis in action See for yourself how and why water moves between different places

1

2

Prepare your experiment

For this experiment you’ll need two glasses, distilled water, some salt and a large potato. Carefully cut the potato into slices of about three centimetres (one inch) across and fill the glasses with water.

Next, place three heaped tablespoons of salt into one of the glasses. Stir until the salt is completely dissolved in the water.

This means one of the glasses will have a slightly lower volume of liquid than the other.

3

Measure your potato slices for length, width and get a feel for how firm they are. You could even take a photo of each one to remind you what colour they are before the experiment begins. Drop a potato slice into each glass of water, making sure you have labelled which of the two glasses has the salty water in it and which one contains pure water. Then you simply leave the potato slices to sit in the glasses overnight.

4

Observe

When you return to the glasses the next day, you should see a marked difference in the two potatoes. The one sitting in the non-salty water should look practically the same as it did the previous night, but the one in the salty glass will not look appetising at all! It should have shrunk, changed colour to a dark brown and, when you take it out, will be limp and mushy. Feel the other potato slice for comparison.

Explanation

This has happened because of osmosis. Everything in nature seeks balance and will alter its state to even out chemical differences. Water is able to escape from the potato through its skin, which is called a semi-permeable membrane. The salty water has a lower concentration of water than the potato, so to even things up, water moves from the potato into the glass of water. This increases the water content of the glass.

5

Other experiments

The water escaping from the potato in the salty water makes it limp and smaller because the water was what gave it its structure and size.

To take this experiment further, try increasing and decreasing the amount of salt in each glass to see how dramatically rates of osmosis can be altered. You can also try different vegetables to see which ones have a semipermeable membrane. If it doesn’t change shape or colour, water has been unable to escape.

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Begin osmosis

In summary‌ This experiment demonstrates how water moves across cell membranes because of osmosis. This process is vitally important to plants, as this is how they gain water through their roots.

Water moves into the plant cells via the process of osmosis and makes them turgid (stiff) so the plant is able to stand upright.

OSMOSIS/GROW BEANS/EGG

Grow beans in Fit an egg into cotton wool a bottle Learn about root formation with a bean and some cotton wool

1

Prepare your ‘garden’

Wash out a small jam jar and stuff it with cotton wool. Toilet paper can also work, but cotton wool holds water for longer. Take a couple of beans, either fresh or dried, and place them either side of the cotton wool, pressed up against the edge of the jar. Butter beans work particularly well because they are large enough for us to observe what happens, but if you don’t have one, this will work with most beans and even legumes like shelled peanuts.

2

Watch it grow

3

Taking root

Water the cotton wool so it is damp but not soaking wet. As the cotton wool holds the water so well, it will provide a steady source of nutrition to the bean. Place the jar in a sunny spot. The beans we eat are seeds, so they will sprout and grow a new plant just like a traditional plant seed.

Within three days, you should see a root begin to grow downward from the bean. A few days later, you should be able to see spidery tendrils grow out from the bean.

A stem should then begin to grow over the following week, pushing your bean upward and out of the jar. The roots will spread out, covering the bottom of the jar.

Eventually, the bean casing will drop off and the plant will begin to grow leaves. The roots grow in any direction where they can receive water, sucking up moisture through their epidermal cells and root hairs. This water gets transferred to the main plant where it is used to help it grow.

Amaze everyone with this clever trick that’s all about air pressure

1

DON’T DO IT ALONE If you’re und

er 18, make sure you have an adult with you

Hard-boil the egg

First you will need to hard-boil an egg by placing it into a saucepan of boiling water for about five minutes. Remove the saucepan from the heat and cover it with a lid, letting it sit for about 25 minutes before removing the egg and dipping it in cold water. Once it has cooled, peel the shell from the egg, revealing the smooth spongy egg white underneath. You could also brush the egg with some vegetable oil to help lubricate it some more.

2

Heat it up

3

The egg falls in

Get a clean, empty glass bottle, making sure the mouth is a little smaller than the narrow end of your egg. Use a lit match to carefully set fire to a couple of thin strips of paper, then drop them into the bottle. This will cause the air inside to heat up and expand as the air particles spread out. As soon as you’ve dropped the lit paper into the bottle, place the egg, narrow-side down, on top.

As the expanding air tries to escape past the egg, you should see it vibrate.

When the fire has consumed all of the oxygen inside the bottle, it will go out and the air will start to cool down. By sealing the mouth, the egg creates a vacuum of this cool air, which takes up less space and exerts less pressure. As the outside air exerts more pressure, it will try to rush back into the bottle, forcing the egg in with it.

In summary…

In summary…

Growing a plant in a jar is an excellent way to see nature in action. The cotton wool helps it both remain stable and provide a constant source of water. Make sure the bean always has water and sunlight so it can grow before your eyes.

To get the egg back out of the bottle, you need to increase the air pressure inside. Do this by turning the bottle upside down and blowing into it. By forcing more air in, you raise the pressure, so when you take your mouth away, the egg should pop back out again.

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G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

Build a lung

Turn everyday household items into a working lung model

1

2

Cut your bottle

With the help of an adult, cut the two-litre (0.5-gallon) bottle in half.

Discard the bottom half and the lid as you will only need the top half for this experiment. Cut a square of plastic from a shopping bag and make sure it is big enough to cover the bottom of DON’T the cut bottle. The DO IT edges don’t need to ALONE be perfectly straight If you’re under 18, make sure so don’t worry about you have an adult with you being too neat.

3

Stand the bottle on its top, and place your cut plastic over the large, open end. With the help of a rubber band, secure your cut plastic around the bottle. Carefully pull the edges, so that a taught surface is formed across the top.

Once you are happy with this, you can trim off the excess plastic. This represents your diaphragm, the muscle that contracts and relaxes, forcing your lungs to fill with air and then empty.

4

Build your breathing mechanism

Install your lung

Drop the balloon end into the bottle’s opening. This needs to be secured in place, which can be achieved using modelling clay. Press the modelling clay down firmly to create a seal, which must be completely airtight just like we did with our tape and straw in Step 3. The model won’t work if air is able to enter the bottle by any other means than the straw.

You are now ready to add your breathing mechanism. Place a straw inside a balloon, which will act as a lung. Next, secure the straw in place with plenty of tape, as this seal will need to be airtight. Now test the seal by blowing into the straw; if the balloon doesn’t inflate slightly then the seal needs to be improved by being tightened up some more.

5

Complete your model

The final step is to add a kind of lever so you can move the plastic sheet up and down. Putting a sticky tape ‘tab’ to the bottom of the plastic will achieve this. Take a piece of tape and fold it in half, so that the sticky sides are together and the ends are left exposed. Stick the exposed ends onto the middle of the plastic sheet securely, so that it can be pulled gently without it coming off, moving the plastic in and out.

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Secure your plastic sheet

In summary…

This experiment cleverly illustrates how we breathe with simple househould objects.

When the diaphragm contracts in our bodies, air is able to enter the lungs due to the extra room this creates. When you exhale however, the diaphragm relaxes, forcing air out of your lungs. This is shown when you pull down and push up on the model’s plastic sheet.

LUNG/CHROMATOGRAPHY/SOUND

A DIY chromatography test Find out how to separate inks into their different coloured components

In summary…

1

Prepare your test strips

The first step for any chromatography test requires the test strips to be prepared. Cut some filter paper into strips, 1.3 centimetres (0.5 inches) wide. The length of the strips is dependent on the height of your cup, so make sure you cut them accordingly. Take your test pens and draw large dots 1.3 centimetres (0.5 inches) from the bottom of the strips, making sure you only use one pen per strip.

2

Mount your test strips

Take a wooden stirrer and secure the test strips to it, so that when the stirrer is rested across the top of your cup, the strips will hang down into it.

There are a number of ways of attaching the strips to the stirrer, but we think the best way is by making use of a bulldog clip. However, taping the strips to the stirrer will also work just as well. If you don’t have a stirrer to hand, a pencil or pen will do the same job.

3

Add your solvent

Now add the solvent, which travels up the filter paper and separates the inks. Pour some water into each cup so that the water just about touches the bottom of each test strip. If the test dots become submerged they will separate out without travelling up the paper.

Leave the strips hanging in the water until the inks have separated and the different colours have nearly travelled the length of each strip.

As water moves up the filter paper it carries certain colours with it.

Some colours move further up the paper than others due to differences in their solubilities. In today’s laboratories, chromatography is one of the most widely used analytical techniques. Different forms of chromatography are used to test blood and alcohol in forensics and are also used to separate out food dyes.

Learn about sound waves A simple experiment to show how sound travels and why it changes its pitch

In summary…

1

Prepare your experiment

Half-fill a glass with water and set it aside. Next, cut horizontally through a drinking straw around two-thirds of the way up. You want to be able to bend the smaller third at right angles without breaking the straw. Be prepared to have several goes at this before getting it right, as it is quite a delicate operation. Once you have successfully cut through the straw, place the larger part into the glass and bend the smaller part back.

2

Make some music

The smaller part of the straw should be bent so that when you blow through it, the airflow passes along the top of the straw. Blow gently into the tube. You should be able to hear a whistling sound. This sound is created as the air inside the larger part of the straw vibrates. The vibrating air travels down the straw, hits the water and bounces back up.

Once out of the straw again, the sound waves expand, reaching your ear as a whistling noise.

3

Pitch up

To take the experiment further, see how the pitch changes as you increase or decrease the volume of water in the glass. You should notice the pitch gets higher with more water in the glass. This is because the pitch of sound is determined by the speed of the vibrations. With more water in the glass, the straw is fuller and the vibrations have less time to stretch out. This increases the speed of the vibrations, making the sound that reaches your ear much higher.

This is an easy way for you to understand the properties of sound and how it can be manipulated. Sound comes from vibrations and by speeding them up or slowing them down, we can make sounds higher or lower. This is something we do every day without realising it when we talk.

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G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

SPECTROMETER Split light into its constituent colours and learn about atoms with this easyto-make gadget

ST EP 1

Step 2. Next, take the remaining piece of black card and place the kitchen roll tube upright on top of it.

Draw around it with your pencil and then remove the tube. Cut roughly around the outer circumference, ensuring that you leave a centimetre overrun at all points (ie the cut-out circle is a centimetre wider than the tube’s circumference).

Spectrography is an incredibly useful process for scientists and astronomers, which enables them to investigate the chemicals found in objects located trillions of miles from our planet. This is because the atoms of different elements – which in various combinations make up every part of the universe – have their own distinct patterns, and by observing these patterns scientists can determine what an object, such as a star, is made of.

Spectrography is not all about observing space, however; it also has numerous applications in the laboratory here on Earth, or indeed your very own home for educational purposes. By following these five simple steps, you too can investigate light and study it on an atomic level with your very own spectroscope.

ST EP 2

Equipment: 1 x kitchen roll tube 2 x A4 black card 1 x transparent CD 1 x Roll of packing tape 1 x Pencil Some glue 1x Pair of scissors 16

Step 1. Okay, first take your kitchen roll tube and insert the black card so that it lines the interior wall.

When you have a tight fit, carefully pull out the card and tape it at the desired point, before cutting off any excess at either end. Once the black card is a single tube, slot it back inside. If you have done this correctly, the black card should hug the kitchen roll tube’s wall snugly.

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MAKE A SPECTROMETER DISCLAIMER

Under no circumstances use your spectroscope to look at the Sun or an artificial light source for a prolonged period of time. Further, when using your spectrometer, never look through it with either of your eyes pressed to the viewing screen – instead always observe from a minimum distance of 15 centimetres (six inches). Finally, in following this guide, you agree that neither Future Plc nor any of its employees are in any way liable for potential injury or unwanted side effects to your person.

ERS

ST EP 4

ST EP 3

A

B Step 4. If you have followed the previous steps closely you should now have something like this. If so, take your CD and stick it onto the other end of the kitchen roll tube. Importantly though, do not stick it in the centre of the disc; instead stick it over one of the transparent edges. You want to be able to look through the CD into the tube. Above you can see the ideal setup.

Step 3. Once you have your circle of card, cut out a rectangle in the middle then stick it to one end of the kitchen roll tube. Next, taking the remaining card, cut two smaller rectangles and tape them either side of the central rectangle so that only a narrow slit is left open. It’s very important that the final slit is straight and level at either side (as per the image).

ST EP 5

Stop!

Science time!

© NASA

Step 5. Finally, after checking everything is secure and that there are no gaps in your spectroscope, hold it up to a bright light source – such as a light bulb – while looking through the CD end of the tube; do not put your eye directly to the CD, but rather stand off by at least 15 centimetres (six inches). If you have made the scope as instructed, a colourful, rainbow-like spectrum should appear on the transparent surface of the disc. This works especially well if you cover one of your eyes.

So what is happening and how does this work? The spectroscope is splitting the light into its constituent colours, which are determined on an atomic level. The CD screen acts as a diffraction grating, bending light as it passes through, filtering the wavelengths of the white light (white light is a mixture of all wavelengths) in the process. This is why a rainbow-like array of colours is presented to the human eye. As such, each time you look through the spectroscope at a different light source, the spectrum of colours will vary, determined by the wavelengths it is emitting. Test it out on a few different lights!

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Make a pinhole camera Turn an empty Pringles tube into a simple camera

1

2

Cut your tube

With the aid of a ruler, measure five centimetres (two inches) from the bottom of a Pringles or similar cardboard tube and mark this distance with a pen. Repeat this around the tube and then join up to marks so that you create a line that goes all the way around it.

DON’T Carefully cut along DO IT this line, separating ALONE If you’re under the cardboard tube 18, make sure you have an adult into two pieces. with you

3

You then need to make a hole in the centre of your crisp tube’s metal base. There are several techniques for achieving this; whichever one you choose needs to be able to create a very small, smooth hole. We recommend tapping a pin with a heavier object, but making sure to twist it as you push it through the metal, creating smooth edges. This pinhole is an example of a camera’s aperture.

4

Design your viewing screen

Make it ‘light-tight’

A pinhole camera relies on the premise that the only light entering it is through the pinhole. This means light must be unable to penetrate the camera’s body. To make it ‘light-tight’, wrap the camera in aluminium foil. It is worth wrapping the camera several times in foil to guarantee it blocks out all light, and taping it to the camera to ensure it stays intact.

Now to create your viewing screen, which acts as the film.

Cut out a circle of waxed paper, making it slightly bigger than the tube’s base, and tape it on top of the short part of the tube.

The image you’ll eventually see here will be inverted and reversed, as the light rays cross over when entering the camera.

Reform your crisp can by taping the two pieces back together.

5

Finishing touches

The final part of the camera requires a piece of thick black card. Roll the card into a cylinder and place it halfway into the top of the camera. This helps to shield the camera’s eyepiece from any light, which will improve the visibility of the image the camera creates. To use your camera, simply place an object under a bright light and point the pinhole end at it. You will then see a colour image on the viewing screen within the camera.

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Make your pinhole

In summary…

This experiment provides an excellent insight into the origins of the camera in Victorian times, and can be carried out using readily available household materials. The images you see as you look through the camera will be upside down and back to front because of the way light travels through the tiny gap.

PINHOLE CAMERA/PAPER/INK

Create recycled paper

DON’T DO IT ALONE If you’re und

Take your unwanted mail and turn it into original handmade paper

er 18, make sure you have an adult with you

In summary…

1

Make your deckle

The first step required to make your own recycled paper is to construct a deckle, which functions to strain the watery paper pulp you are going to create in the next stage. Use staples or thumbtacks to fasten strong netting on one face of a small wooden frame, such as an empty picture frame. Another potential deckle design involves stretching a piece of nylon stocking over a sturdy hoop, such as an embroidery hoop. This would also function well as a pulp strainer.

2

Form your pulp mix

Shred your paper into rough chunks; you’ll need enough to fill your blender by half. Add warm water until the blender is full, and then blend until it forms a pulp, free from large chunks of paper. Blending helps break down the paper’s cellulose fibres. Decant your pulp into a large plastic container and add another blenderful of warm water and mix, which helps bind the broken fibres. You can now add food colouring to create coloured paper.

3

Create your paper

Place your deckle into the plastic container with the screen submerged just below the pulp’s surface, allowing an even collection of pulp on top of the screen. Remove the deckle and gently shake it to drain most of the water. A sponge can also be used to remove excess water. Carefully press a clean kitchen towel on the paper, pull it away from the screen and let it dry before peeling it from the towel. If the paper is too thin, add more pulp; if it is too thick, add more water.

This fun experiment will require some trial and error to perfect, but it is an excellent way of making something interesting and handmade out of unwanted waste paper. Try adding some dried grass or thread into the pulp mix to give your paper an unusual texture.

Make invisible ink

Learn how to write secret messages that can be revealed by the power of heat

In summary…

1

Prepare your lemon juice

Take a lemon and cut it in half with a sharp knife, with the supervision of an adult if necessary. Squeeze half the lemon, using a lemon squeezer or by hand. Pour the lemon juice into a separate bowl and add a few drops of water. This dilutes the lemon juice, making it near impossible for anyone to see with the naked eye once your message has been written on paper.

This is because lemon juice contains carbon compounds that are colourless at room temperature.

2

Write your message

Take a writing implement and dip it into your lemon juice mixture.

We recommend that you use a cotton bud, but other options such as a brush, a dry fountain pen or even a feather will work too. Take a plain piece of white paper and carefully write out your message, remembering to dip your writing utensil regularly to ensure it has plenty of lemon juice on it. When you are finished, leave the paper to dry in a safe place.

3

Reveal your secret writing

You can tell when the paper has dried because the message will be completely invisible. Pick the paper up and slowly heat it, near a hot incandescent light bulb or with a hairdryer. Slowly but surely, your secret message will appear! This experiment works because the heat breaks down the compounds in the lemon juice, releasing carbon. When the carbon comes into contact with the air, it starts a process called oxidation, which turns it brown.

The diluted lemon juice is colourless at room temperature, allowing your message to stay secret until heat is applied. As you warm up the paper, the carbon compounds in the lemon juice release their carbon, which reacts with oxygen to turn those parts of the paper brown, revealing the secret message on it.

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Red cabbage litmus paper Try this cheap and easy way of testing whether a substance is an acid or a base Test the pH of any substance you like, including lemon/lime/orange/tomato juices , milk, soapy water, vinegar, household bleach (warning: mixing bleach and ammonia will create toxic fumes so never mix household cleaning products), window cleaner, baking soda (note: when testing solids or powders, you will first need to dissolve them in a small amount of water) or powdered laundry detergent.

1 x Small red cabbage 250ml Tap water 1 x Grater or knife 1 x Sieve 1 x Bowl 1 x Sheet of plain white paper 1 x Scissors 1 x Tweezers (optional) 1 x Wire rack

Step 01

Step 02

Take the red cabbage and finely slice or grate it. You won’t need the whole cabbage, just a piece of it. But slicing it thinly means the indicator molecules inside will be released into Step 2’s hot water quicker.

Put the chopped cabbage into a pan containing about 250ml of boiling tap water and simmer for 20 minutes on your kitchen hob. The solution’s concentration will be stronger if you use a little bit of water.

Step 03

Step 04

Now, take the sieve and, while holding it over the bowl, pour the cooked cabbage and the hot water mixture into the sieve. You now can either discard the cooked cabbage or make a tasty treat with it.

Leave the coloured cabbage water to cool down. This will allow you time to prepare the paper for the acid test in the final step.

Chop

Strain

20

Equipment:

Boil

Cool

RED CABBAGE LITMUS PAPER

Step 05

Step 06

Take the sheet of paper and cut it into two-inch strips, then into half lengthways, just like the litmus paper you used at school all those years ago.

Cut one strip for each substance whose alkalinity you would like to test. 

Now that the cabbage water has cooled, place the strips of paper into the bowl and leave them to soak up the purple dye.

The longer you leave it the more colour will be absorbed by the paper, so please be patient.

Paper

Step 07 Dry

Once the paper has turned a good purple colour, carefully remove the strips from the water (we used tweezers to limit our messy fingerprints getting everywhere) and place them on a wire rack to dry. 

Step 08 / Test The dry strips will now look like proper litmus paper so now you can begin to test the pH of various substances. Take one strip and add a drop of your chosen substance, then watch to see what colour the paper turns. In the scale for this red cabbage litmus test, the pH for each colour is as follows 0-2: Pink 3-4: Dark red 5-6: Violet 7-8: Blue 9-10: Blue-green 11-12: Green 13-14: Yellow

Soak

Th e pH sc al e What do the results tell us?

The pH scale measures the concentration of hydrogen ions in a solution, telling you whether it is an acid or a base. An acid has a high concentration of hydrogen ions while a base has a low concentration. The scale ranges from 0 to 14, and while a substance with a pH of seven is neutral, like distilled water, anything below seven is acidic, and anything above seven is alkaline, or basic. Each pH value below seven is ten times more acidic than the next highest value. pH4, for example, is ten times more acidic then pH5, and 100 times more acidic than pH6.

Table to show the pH scale Concentration of pH hydrogen ions to distilled water

Examples of solutions and their pH

1/10,000,000

14 Base

Liquid drain cleaner, caustic soda

1/1,000,000

13 Base

Bleaches, oven cleaner

1/100,000

12 Base

Soapy water

1/10,000

11 Base

Household ammonia (11.9)

1/1,000

10 Base

Milk of magnesium (10.5)

1/100

9 Base

Toothpaste (9.9)

1/10

8 Base

Seawater, eggs

0

7 Neutral Distilled, pure water (7)

10

6 Acid

Urine (6), milk (6.6)

100

5 Acid

Acid rain (5.6), black coffee (5)

1,000

4 Acid

Tomato juice (4.1)

10,000

3 Acid

Grapefruit/orange citrus juices, soft drink

100,000

2 Acid

Lemon juice (2.3), vinegar (2.9)

1,000,000

1 Acid

Hydrochloric/sulphuric/nitric acids (1)

10,000,000

0 Acid

Battery acid

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Extract your own DNA

Collect a sample of DNA from your cheek cells with this great home experiment

1

2

Prepare your alcohol

For this experiment to work you need to get some highly concentrated alcohol. This can be easily obtained from your local pharmacy in the form of isopropyl alcohol. The closer you get to 100 per cent alcohol, the better success you will have. Around 24 hours before you start, place your alcohol in the freezer. It won’t solidify due its very low freezing point, but needs to be ice cold for the experiment to work.

3

Take a generous mouthful of a lightly coloured sports drink and swirl it around your mouth. Aim to keep this going for a minimum of two minutes, which is a lot harder than it sounds. To get as many cheek cells and therefore as much DNA as possible, gently scrape the inside of your cheeks with your teeth. Be careful you don’t scrape too hard, we don’t need any blood for this experiment!

4

Set up your test tube

Spit the mixture into a paper cup and pour the solution into a small, clean jar or a test tube, filling it by one third. Add a little dish soap, fasten the lid and then carefully mix the solution, slowly turning it upside down. The soap breaks down the cell membranes, releasing the DNA. Add a few drops of pineapple juice and repeat the process, ensuring you don’t create any bubbles.

er 18, make sure you have an adult with you

22

Add your chilled alcohol

Remove your alcohol from the freezer and take the lid off your mixed cheek-cell solution. While tilting the container in one hand, trickle the alcohol down the inside of the container so that it gradually forms a layer that floats on top of the solution. Once you are happy that a good layer has formed, slowly return the test tube to an upright position and then leave on a flat surface for one minute.

5

DON’T DO IT ALONE If you’re und

Produce your cheek-cell mixture

Extract your DNA

Once one minute is up, have a look at the alcohol layer floating on top of the solution. If you can see a band of white material between the alcohol and the rest of the solution, your experiment has worked! This is your DNA, and it can be extracted using a wooden skewer. Dip the skewer into the solution so that it touches the white material, and then twirl it slowly in one direction. This should wind the DNA in a strand around your skewer. You can now store your DNA in the freezer or examine it using a microscope.

In summary…

Gentle mixing of the soap and sports drink solution makes sure that the DNA clumps don’t break up, which makes the extraction process much easier. This experiment relies on the fact that DNA does not dissolve in alcohol, which forces it to precipitate out from the sports-drink solution when this contacts the alcohol layer.

DNA/SUGAR CRYSTALS/HEART

Make sugar crystals Study the formation of crystals and make a tasty treat!

In summary…

1

Prepare your sugar solution

Start off by boiling some water using either a kettle or a pan. Ask an adult to help you with this just in case of any accidental spillages. Once you’ve got your boiling water in a pan, carefully add sugar one spoonful at a time, making sure that you don’t touch the pan or cause any of the boiling water to splash around. It’s key that you have as much solute dissolved in the solution as possible, as this will increase the chances of your crystals forming.

2

Set up your glass jar

Once you’re satisfied that you’ve dissolved as much sugar as possible, add a few drops of red food colouring to give your rock candy some colour.

Being extra careful you don’t spill any, pour the solution into a clean jar (it has to be clean as otherwise sugar crystals will bind to any dirt in the jar). Tie a piece of string around a butter knife, making sure it is long enough to hang into the solution but doesn’t touch the bottom or the sides of the jar.

3

Leave to grow

The set up of your jar is now complete and needs to be left for a week to allow the crystals to grow on the string. We recommend that you leave your jar in a safe, dry area, where it won’t be exposed to lots of dust or debris. It’s also vital that the jar isn’t knocked or moved in any way, as this would disrupt crystal formation on the string. Once you are happy with their growth, lift the knife up and remove the crystals. When they are dry, this colourful sweet treat is ready to enjoy!

The substance you’ve created is essentially a primitive form of rock candy. The crystals grow due to their tendency to clump together at a molecular level, which happens when they bump into each other in solution. This process is known as nucleation, and will readily occur in solutions that contain high concentrations of solute.

Make a model heart chamber See how the amazing muscles in your heart keep blood pumping around your body

In summary…

1

Fill your jar

Take a medium sized beaker or a wide-mouthed glass jar, and half fill it with water. You will then need a large balloon, which will work to seal off the inside of the beaker. Cut the balloon at the neck, just before the part that widens into the main balloon. Don’t throw away the small neck part that you’ve cut off, as you will need it later in the experiment to help the construction one of your heart’s valves.

2

Attach your balloon

Take your balloon and stretch it over the opening of your glass jar or beaker, making sure you pull it down as tightly as you can so that it holds itself securely in place. The flatter you can get the surface of the balloon, the better. Take a sharp skewer and carefully poke two holes into the flat surface you’ve created, roughly 2.5 centimetres (one inch) apart from each other, at opposite sides of the jar.

3

Complete your pump

Stick a straw through each hole, making sure it fits securely. Air should only be able to enter or leave through the straws. Tape the small part of your cut balloon around one of the straws. Place the jar in a large pan in case of spillages, then bend the straws downwards and gently press in the centre of the stretched balloon. Water will be forced out through the straws, simulating your heart pumping blood.

This simple experiment simulates one of the heart’s four separate chambers.

The balloon on the end of one of the straws acts as a valve, stopping blood from re-entering the chamber it has been pumped from.

Without these valves, the heart would not be able to transport blood from chamber to chamber and then around the body successfully.

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DISCLAIM ER

Making an el be dange ectromagnet can electromag rous. Never put the net and do not near a mains socket battery or touch the ends of the , the the circuit exposed wire when is perform th connected. Always e adult prese experiment with an nt. Im and its staff agine Publishing responsibl cannot be held e for as a result injury caused of mak electromag ing an net.

An electromagnet Most of us remember doing experiments back at school, and some of you readers are still doing them. If there’s one thing that stuck in our mind from back then it’s that they were often long and tedious.

Well, How It Works is here to liven things up. We’ll be taking some of the best experiments that can be done at home with basic equipment and giving them a rundown in our laboratory, and we’ll show how you can re-create them at home. Just like at school we’ll go through how each experiment works, only this time you won’t fall asleep halfway through.

We’re giving science a boost of excitement starting this month with electromagnets.

An electromagnet is a device that uses an electric current to produce a magnetic field. And making your own electromagnet is a great way of understanding the basic principles of magnetism and electric current. Show your mates or your family and it’s also a lot of fun.

We show you how to build and experiment with homemade electromagnets ST EP 01

1. Before we get started, a word of warning. The battery and wires can get hot, so be careful when handling them. Good? Great. First, cut off a section of wire, enough to wrap around the nail several times depending on how many coils you want. You also need to leave a bit of leeway at either end so that some of the inner wire can be attached to the battery. To do this, lightly cut the wire with scissors or wire cutters and pull the outer casing off.

ST EP 03

Equipment: 2 x 1.5V D batteries 3 x 50mm nails 1 x T hin insulated copper wire 1 x S ticky tape 1 x S cissors/wire cutters 1 x P aper clips 24

ST EP 02

3. Attach the ends of the wire to the positive and negative ends of the battery (it doesn’t matter which way round). Tape both the ends on to keep them in place, but be careful not to leave them on too long as it can get quite hot.

2. Wrap the wire around the nail and extend each end as shown, but be careful not to overlap the coils. The one in the image has 25 coils, but how does it work? Well, when electricity flows through a wire it creates a small ring of magnetism. By coiling the wire the magnetic field is amplified, as there are more and more magnetic rings. The wire will magnetise a metallic object if wrapped around it when current is flowing.

CRAFT AN ELECTROMAGNET ST EP 04

A

B

4. When both ends are held to the battery, the nail will become magnetised. Notice that the paper clips stick to both ends. Even when the battery is taken away, the nail retains some magnetism for a brief period of time.

ST EP 05

ST EP 07

A

C o m p le te d !

B 5. We tested out electromagnets with different numbers of coils. Here, we’ve got our original 25 coil, a 50 coil and a 75 coil electromagnet (we taped them at the end to stop the wire springing off). You can do many more experiments to see how different variables affect the strength of the electromagnet such as the length of the wire, the type of wire used and the number of batteries.

ST EP 06

6. Here, our 75 coil electromagnet is shown picking up some paper clips. We found that the number of coils was almost directly proportional to the number of paper clips it could hold. Our 25 coil magnet held ten paper clips, but our 75 coil electromagnet held almost exactly three times as many at 31 paper clips. This means that as more coils are added, the strength of the magnetic field increases.

7. Your electromagnets are complete, and you are free to experiment and try out different arrangements. We added an extra battery to see the difference in strength, and found that our electromagnet was able to pick up its own weight in another nail, although it struggled with our heavy scissors.

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Explore Isaac Newton’s first law of motion with some simple items If you’ve ever wanted to put a scientific theory into practice at home then now’s your chance. Sir Isaac Newton’s first law of motion helps explain the motion of conventional physical objects and systems. He implies that any object at rest will remain at rest unless an unbalanced force acts upon it.

So, if you were to place a tennis ball in space and give it a bit of a shove, its momentum will keep it moving at the same speed and in the same direction unless something bumps into it, and if left untouched its inertia will keep it in the same place.

On Earth, however, Newton’s law is seemingly complicated by the permanent forces of gravity and friction, the former constantly pulling them towards the ground while the latter slows them down.

Does this disprove Newton’s law?

No, far from it. In fact, these forces help demonstrate its high probability, as can be seen at home in a simple and easy-to-construct experiment. Let’s get started…

Penny drop Step 1. Take your card and cut it into long thin strips vertically roughly 2cm wide, then tape the ends together so it forms a hoop.

This experiment works best when the hoop is 8-10cm across.

However, for variables to the experiment, take another two strips and make one smaller hoop and one larger.

A

ST EP 1

B ST EP 3

Equipment: 1 x s heet of card (coloured card looks nice) 1 x glass jar 1 x cup of water 1 x p enny (any coin will do, however this is called the penny drop experiment!)

1 x pencil 1 x Sellotape 1 x s election of other coins of various sizes 26

Step 2. Next, take your glass jar and fill it with water roughly 2/3rds up. The water adds an extra level of data return, as we shall see later, so it is best used.

ST EP 2

Step 3. Third, put your water-filled glass on a level surface and then place the hoop on top of it, so that it radiates out from the centre of the jar like the face of a fan. Finally, place your penny on top of the hoop so it is directly above the glass jar. The card hoop should support the penny and maintain its form if done correctly. If the hoop deforms, you need thicker card.

PENNY DROP EXPERIMENT

p experiment Stop! Science time!

So how does this relate to Newton’s first law? Well, currently the penny is at rest, its inertia keeping it in the same place. Gravity, one of Earth’s meddling forces, is also being counteracted by the hoop, which itself is fixed in position by the neck of the jar. With gravity taken out of the equation and friction negligible, Newton’s law is currently ringing true.

ST EP 4

A

Step 5. Right, before anything else, repeat the last step but this time use either the smaller or larger hoop, or a smaller or larger coin. If replicated correctly, you should notice how the success rate of the coin dropping straight down into the jar when using the larger hoop/coin is less than before, while greater if using the smaller hoop/coin. Finally, notice how the coin’s speed decreases as it travels through the water – this shows an increase in friction over Earth’s standard atmosphere.

ST EP 5

A

Stop!

Science time!

Step 4. Okay, action time. Take your pencil and hook it through the hoop. Now move your hand so the pencil is hovering by either the right or left side of the hoop at is equator. Now in one swift movement, whip the hoop to the side – just like a waiter whipping a tablecloth away – and watch the results. If you have performed this step correctly the penny should drop straight down and land in the glass of water, eventually resting at its bottom. If this does not happen – ie, the penny falls to one side of the jar – try again with a faster hand movement.

B

C

D

When the original hoop was whipped away, the force counteracting gravity was removed, allowing it to exert its influence on the coin. The speed of the hoop’s withdrawal also mitigated the effects of friction on the penny’s centre of mass.

Consequently, the coin was left suspended in the air with just the force of gravity to pull it down in a straight trajectory into the glass. If the coin were in the vacuum of space, however, with no gravitational force impressed upon it, this would not happen.

The increased/decreased contact area between the hoop and the coin affects the level of trajectory-altering friction, with the larger hoop inflicting more and the smaller one less.

Consequently, if there did not have to be any contact between the coin and the hoop, there would be no physical friction – atmospheric drag remains though – and the coin’s straight course would not be altered.

B

Co nc lu si on While Newton’s first law of motion may initially seem inconsistent with our experience on Earth, those experiences are in fact consistent. Simply put, an object will remain stationary or moving in a straight line, providing no auxiliary forces act upon it.

For us on Earth, though, any object (including human beings) will always naturally be impressed upon by the forces of gravity and friction.

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DISCLAIM ER

As mention can make ed, this experimen be sure to quite a bit of mess, t cove so etc before r any tables, carpet conduct th you begin. Always an adult preis experiment with the individ sent, and although u edible, we al ingredients are wou advise agai ld strongly n consumptist any on.

Non-Newtonian This month sees the unveiling of our brand new home experiment section. We’re here to liven up those school lessons and inject fun into science, explaining how some cool experiments work.

For this bit of research we decided to use some simple ingredients to make a remarkable substance. We’d heard that mixing cornflour and water could make a liquid that became a solid when pressure was applied.

We headed down to our lab and made a right old mess as we set about putting Newton’s laws under scrutiny.

Our task was to make the liquid and run it through a few tests to see how it acted.

Newton’s law for fluids states that the viscosity of a liquid, its resistance, will only change if the temperature of the liquid is altered. We set out to show that at room temperature our liquid would change its viscosity depending on the pressure applied, breaking Newton’s law and becoming a nonNewtonian fluid.

Easy experiments like these are great to do at home with kids or parents, so have a try if you feel like it but just beware of the mess.

Equipment: Some cornflour 1 x bowl or container 1 x Food colouring Some Water 028

It’s a liquid, Jim, but not as we know it… the harder you push it, the more solid it is

Method 2. We stirred in about two parts cornflour to one of water. However, the amount of cornflour/water added will have to be adjusted slightly to create the perfect fluid. Keep adding a bit of both and stir until the liquid is really thick. It should be difficult to stir with force but easy to stir slowly.

ME TH OD 1

ME TH OD 2

A

Method 1. We started by getting all our ingredients together. Be warned, if you plan to re-create this experiment at home it can get a bit messy, so you might want to do it in or around a kitchen sink. We used food colouring to make the goop more attractive, but you can add what you want into the mixture to make it look nice.

RE SU LTS 1

A

B

B

Results 1. When we pressed down on the fluid with a pen, the surface resisted until we used a lot of force. The fluid was too viscous for the pencil to penetrate far, and the harder we pushed the less it moved. However, when the pen was left to sit in the fluid with no pressure downwards, it sank to the bottom of the glass.

NON-NEWTONIAN FLUID

fluid

CO NC LUS ION 1

RE SU LTS 2

Conclusion 1. So, why does our goo behave this way? Well, adding the cornflour to the water changes the reaction time of the liquid. When we normally see liquids, they move so fast that we don’t notice how long it takes them to move. Our goo, unlike a usual liquid, has a finite reaction time, letting us roll it into a ball.

Fi n a l c o n c lu s io n Results 2. We can see that the fluid can act as a solid, but what happens when we pour it out of the glass? Barring a few bits that stuck to the side, the goop flowed out of the glass into our bowl just like a liquid would and settled in the bowl like a pool of water.

CO NC LUS ION 2

Conclusion 2. It is called a non-Newtonian fluid as it doesn’t follow Newton’s rules, which explain how liquids should act. When we let go of the ball of goo, it becomes a liquid again. In this case the more stress on the liquid, the higher its viscosity. This physical change is a result of the cornflour and water mixing but not dissolving, creating a permanent suspension of material that does not settle on standing.

Final conclusion. It’s the starch present in the cornflour that ultimately makes our liquid behave like this. The noncrystalline structures of the starch particles absorb the water. When pressure is applied, more of these structures form, in turn absorbing more water and increasing the thickness of the liquid. Decreasing pressure reverses the process and allows the water to flow freely again. Cool!

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Use a telescope A few steps to help you get to grips with looking at the stars

1

2

Reflective or refractive?

Choose your mount

The first stage for any budding astronomer is to decide what kind of telescope they need. Refractor telescopes use a lens to bend light into the eyepiece and are good for seeing planets and stars. Reflector telescopes use two mirrors to capture light and magnify it so you can see incredible nebulae and distant reaches of the galaxy.

Catadioptric telescopes can see both planets and deep space, but are pricier.

As with the telescope, there is more than one kind of tripod.

Alt-azimuth tripods swing left to right and up to down so are easy for beginners to control.

Equatorial mounts need to be aligned to the North Star where they track the stars across the sky as the Earth rotates. This is especially useful for astrophotography but because of the added tech, an equatorial mount will be more expensive.

3

4

Setting it up

Research the sky

Find a flat, stable surface on which to stand your tripod and extend the legs evenly so there’s no risk of the telescope overbalancing. If you are in an area with lots of light pollution, maybe find a high place to stargaze from, providing it’s safe, of course. Follow the instructions for attaching the telescope to the mount extremely carefully, making sure everything is screwed on tightly.

The easiest and most common way to get discouraged when using a telescope for the first time is to not know what you’re looking for. Go online, download a mobile app or get some stargazing books to learn more about the skies you are going to be looking at. Once you’ve got a solid idea of what is out there and established landmarks in order to help you find your targets, you can begin to stargaze with more confidence.

5

Practice makes perfect

Start out simple. Instead of trying to focus on tiny pinpricks of light many light years away, search for items a little closer to home such as trees and buildings.

Once you’ve managed to get the hang of finding items on Earth, turn your telescope up toward the sky and start searching for easy objects such as the Moon before trying harder-to-spot bodies such as particular planets or nebulae.

30

In summary…

The key to starting out with telescopes is patience and making the right choices for what you want to achieve. Selecting the correct telescope, mount and position takes careful planning, so you need to take your time in working your way up to checking out the most incredible sights in the galaxy.

TELESCOPE / BUBBLES / SILVER

Blow bubbles inside bubbles

Create an incredible double bubble using the science of hydrogen bonds

1

Create your bubble

Fill a glass with 260 millilitres (nine fluid ounces) of cold water, a tablespoon of granulated sugar or glycerine and two tablespoons of washing-up liquid. Mix it together with a few brisk stirs until the sugar has dissolved into the water. Next, carefully snip part of the bulbous end off a pipette. Dip your hand in the bubble mixture and wipe it over a surface, such as a table or worktop, to create a thin film of mixture. This will form the base of your bubble.

Clean tarnished silver

Learn how to return your tarnished silver to its former gleaming glory

1

Prepare your cleaning pan

To begin, you need to find an aluminium cleaning pan for your silver. This pan should be big enough to fully immerse your silver in the cleaning solution, so ensure you choose accordingly. It is imperative that your silver is in direct contact with the aluminium during the cleaning process. If you don’t own an aluminium pan, you can line another one with aluminium foil.

2

2

Prepare your cleaning mixture

3

3

Clean your silver

Blow those bubbles

Dip your pipette in the solution, bulb first. When the end is coated in mixture, blow gently through the thin end until you’ve created a half-sphere bubble on the table. Make sure it is at least ten centimetres (four inches) in diameter. This mixture should be strong because of the sugar content. The sugar molecules hold the water molecules in the bubble, forming hydrogen bonds and stopping it evaporating and bursting the bubble.

Multi-bubbles

Now for the fun part! Dip your pipette in the solution again and push it smoothly but firmly into the bubble.

The hydrogen bonds around the edge of the bubble have pushed the soap molecules apart so the pipette can enter without disturbing the soap and water bonds. Blow gently and create a new bubble inside that one. Dip the pipette again and repeat. The elasticity of the hydrogen and soap bonds allow each bubble to expand as another is blown inside it.

Boil an appropriate amount of water; this will form the base of your cleaning solution. Pour the boiling water into a large bowl in your sink. To the boiling water, add roughly one cup of baking soda for each 4.5 litres (1.2 gallons) of water. Be careful when you do this as the mixture will froth and may spill over, which is why it is mixed in a separate bowl rather than directly in your cleaning pan.

Place your tarnished silver into your cleaning pan and cover it with the hot water and baking soda mixture. The tarnish should start to disappear; if the silver is only lightly tarnished it’s likely to disappear within two to three minutes. If the tarnish is severe, you can reheat your cleaning mixture and treat the silver again. Once you’re happy, dry your silver quickly, as leaving it wet may cause staining.

In summary…

In summary…

This experiment is made possible thanks to the bonds formed by the sugar or glycerine. By stopping the water evaporating they prolong the life of the bubble and by pushing the soap molecules apart they enable the pipette to enter. See how many bubbles you can get inside the original.

Silver tarnishes as it can combine with sulphur and form silver sulphide, which is a black substance that will darken the surface.

In this experiment, the silver sulphide is removed due to its ability to react with aluminium. The sulphur atoms are transferred to the aluminium from the silver, removing the tarnish and forming

31

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC Explore the principles of buoyancy, density and pressure with this easyto-conduct home experiment The Cartesian diver (sometimes referred to as the Cartesian devil) is a classic science experiment created by French scientist René Descartes. It demonstrates the key principle of buoyancy, as well as the implications of the ideal gas law and Pascal’s principle. Most excitingly, however, it can be undertaken with just a few common household objects in less than ten minutes! So grab your metaphorical snorkel and swimsuit, as it’s time to go diving!

Cartesian div ST EP 1

Step 1. Okay, to start take your straw and cut it into two pieces of roughly 4cm (1.5in) in length. Try your hardest to cut the straw so that it is left with even, flat ends. Once the straw has been cut, take one half and apply a small blob of Blu-Tack to each end, ensuring that they form a watertight seal.

Step 2. Once you have your Blu-Tack-sealed straw, place it to the side for a minute and go and fill up your glass two-thirds full with water. Next, place the glass of water on a flat surface and drop in your straw. If you have applied the correct amount of Blu-Tack, the straw should sink then slowly rise to the top of the water and float on the surface. If it sinks to the bottom and doesn’t rise, remove the straw and reduce the amount of Blu-Tack. On the other hand, if the straw bobs on the surface as soon as it hits the water then add some more Blu-Tack to each end.

ST EP 2

Equipment: 1 x Large plastic bottle 1 x Jug of water 1 x Glass 1 x Straw 1 x Blu-Tack sheet 1 x Pair of scissors 1 x Bottle of table salt

ST EP 3

Step 3. When you have achieved the correct Blu-Tack balance, take your large plastic bottle – a two-litre fizzy drink bottle is ideal – and fill it with water. You are now ready to place your straw/Blu-Tack ‘diver’ into the bottle. After dropping the straw in, top up the bottle to the rim of the neck with extra water (there should be no air-space left in the bottle). Once it’s topped up, screw its lid back on.

32

CARTESIAN DIVER EXPERIMENT

ver experiment ST EP 4

Step 4. Not impressed so far? Well, here comes the action part. Take hold of your bottle with one hand and squeeze its plastic sides firmly. Note how the straw diver proceeds to sink towards the bottom of the bottle. Now let go of the bottle’s sides. The sunken diver should float slowly back to the top of the bottle.

Both actions have been caused without any direct contact with the diver, with its weight apparently increasing and then decreasing again purely by you squeezing the bottle.

ST EP 5 Co nc lus ion

Sto p! Sc ien ce tim e!

So why does squeezing the bottle affect the apparent buoyancy of the straw diver?

Key to its behaviour is the sealed air within the straw.

The combined density of this air, along with the straw and the Blu-Tack, is lower than that of the water, causing the diver to float at the top of the bottle if left untampered with. When you squeeze the sides of the bottle, however, the exerted pressure on the diver increases, as there is less volume within the bottle for the water and the diver to inhabit. Now, the pressure change – which is very low – is not great enough to compress the straw or the Blu-Tack, but it is powerful enough to compress the sealed air bubble. This compression causes the air bubble to gain density and, as a direct consequence, the diver too, taking it to a level where it is greater than that of the surrounding water. In contrast, by releasing your grip from the plastic bottle, the air bubble is allowed to expand in volume to its original size, returning the diver’s density to its previous state, which is less than that of the surrounding water. As a result, the diver floats back up to the top of the bottle.

Step 5. Now it’s time to add a variable to the experiment. Remove the diver from the bottle and add a generous sprinkling of salt to the water. Once this has been added shake the bottle vigorously for 30 seconds until no sediment rests at the bottom. Now repeat the experiment’s fourth step. What happens when you squeeze the bottle? Does the diver sink as before, or does it remain at the top of the bottle? Or does it necessitate you to squeeze harder than before in order to generate the same diving motion?

So what have we learned here? When constructed correctly, the diver traps just enough air inside its body to make it positively buoyant, allowing it to float near the water’s surface.

When the bottle is squeezed, however, due to Pascal’s law – pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio remains the same – the water’s pressure increases and exerts that pressure upon the diver’s central air bubble. This causes the air to compress and reduce in volume. The diver now displaces a lesser weight of water than its own weight and becomes negatively buoyant, thus sinking to the bottom of the bottle.

33

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC How water breaks free of gravity to rise inside a glass Science can be fun. No, really, we mean it. Even cheap and easy-tofind things in and around your house can be used to prove and disprove a wide range of theories, and most of them are a lot of fun.

One of the best things about doing these experiments at home is that you can muck about with them and add variables, or test different materials to get different results. If you get an urge to set about trying to disprove Newton or confirm Einstein’s musings, there’s always potential to experiment within an experiment.

This practical test is a really simple way to show the effects of Charles’s law (which we’ll explain further in a moment) on a liquid, and it’s also a lot of fun to watch the resulting effects. We decided to take this experiment further by adding a few extra variables, but if you decide to re-create it and can think of anything else to change, then get in touch.

Equipment: 1 x Dinner plate 1 x Drinking glass 1 x Food colouring 1 x Candle 1 x Lighter

Anti-gravity Me tho d 1

Method 1. The great thing about this simple experiment is that it proves some pretty complex science in a matter of seconds. The first thing you’ll want to do is mix some food colouring in with your water, to make it easier to observe the effects later.

Me tho d 2

Method 2. Next, pour the liquid into a shallow dish or plate. This needs to be flat at the bottom so that the candle and glass are on an even surface and the water level is horizontal, not at an angle.

Me tho d 3

DISCLAIMER

While this experiment is relatively simple, the use of a flame can still be very dangerous. Always carry out the experiment under adult supervision. Never hold your fingers close to the flame, and ensure that your candle is secure so that it doesn’t fall over.

34

Method 3. Place the candle in the centre of the coloured liquid and carefully light it with matches or a lighter, without burning your fingers of course. Then, place the glass, at room temperature, over the candle and record what happens next…

ANTI-GRAVITY WATER “Charles’s law states that the volume of gas is directly proportional to the temperature”

y water

Re su lts 2

Re su lts 1

Results 2. The water remains at this level in the glass and does not flow back out. In addition, when you lift the glass in the liquid, you’ll notice that even more water rises. So, what’s going on?

Co nc lus ion 2 Results 1. First you’ll notice that the water level rises very slightly as the candle begins to go out. Suddenly, as the candle is extinguished, the water level inside the glass dramatically rises, before coming to a halt.

Col d: 3.4 cm

Hot : 1.9c m

Co nc lus ion 1 Conclusion 1. This experiment is largely a result of Charles’s law, which states that the volume of gas is directly proportional to the temperature. In this experiment, the candle significantly increases the temperature of the air within the glass.

When the candle goes out, the temperature drops significantly and thus so does the volume of gas and the pressure inside the glass.

However, outside the pressure remains the same, resulting in the water being pulled up into the glass.

Conclusion 2. Many people often credit this effect to oxygen being used up within the glass. This is incorrect, as noted when the water level only rises significantly once the candle has gone out and not before. To prove our conclusion, we then re-created the experiment with a glass chilled in the freezer and another placed in hot water.

We noticed that the hot glass had a much lower rise in water, whereas the water in the cold glass went much higher. This is because in the hot glass, the air inside was already warm. The change in temperature when the candle went out was not very big, and thus the pressure only decreased slightly. In the cold glass, however, the drop in temperature when the candle went out was large, resulting in a bigger drop in pressure and subsequently more water being drawn into the glass.

35

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

DO TRY TH IS AT This is a gr HOME!

eat experi budding ment you’ll be amscientists of all agesfor and azed out ho do, so h w easy pictures in ave a go and send yo it is to to u r ho witworks@ publishin imagineg.co.u experimenk. Always carry out supervisio ts with adult n and, do not con of course, su the liquid.me

Exploding colour We’d heard about a pretty cool effect when soap is added to milk and food colouring, so we decided to give it a try and work out exactly what was happening.

Suffice to say, the results were colourfully explosive.

Our task was to use two variables, water and milk, and see the difference when we added soap to the mix.

Our hypothesis predicts that there should be little to no effect in water, but repeating the process in milk should produce a colour explosion.

You can read through our method, results and conclusions here, but it would be great if you guys have a try and send in some photos of what you created. Maybe you could change some of the variables, using oil and other liquids, or see if something other than soap will produce the same effect.

If you’re planning a science project, educating students or just looking to amaze your friends, this fun experiment produces some amazing results. You’ll probably find all the things you need in your kitchen cupboard, so there’s no excuse not to try it!

We combine food colouring, milk and soap to produce colourful results Me tho d 1

Method 1. With all our apparatus together, we set about testing our experiment with our first variable: water. After pouring water into a shallow plate, we then added food colouring, which settled as a blob in the middle, before adding a bit more for science (and definitely not just to make it look nicer).

B

A

Re su lts 1

A

B

Equipment: Some washing - up liquid 1 x Food colouring Several cotton swabs Some water 1 x Dinner plate Some milk 36

Results 1. We left the food colouring to settle for a minute or so, and then collected some of our washing-up liquid on the end of a cotton swab. We dipped the swab into the centre of the pool of colouring and, as our hypothesis correctly predicted, nothing happened. Would the same be true when we used milk?

MAKE EXPLODING COLOUR

Me tho d 2

Co nc lus ion

Method 2. We poured milk (it’s best to use whole milk, we’ll explain why later) into the same plate, with the water removed of course. Again, we added food colouring, which immediately looked different to our water method. The colouring was clumping together, rather than spreading out uniformly.

Re su lts 2

Conclusion. The key to this experiment is the fat and protein in the milk, which is why we used whole milk. When the soap is added, it reduces the surface tension where it is applied by changing the bonds in the molecules of the protein and fat in the milk. Outside the influence of the soap the surface tension remains high, so the outer milk pulls the central milk near the soap away. The food colouring follows these currents and produces this neat effect. Once the surface tension is uniform in the liquid, the process stops, as you can see in our separate example using just green colouring.

B

A

c Results 2. Again, we dipped a cotton swab into our washing-up liquid and introduced it into the centre of the food colouring. This time, the food colouring receded away from the soap in an ever-expanding swirling circle, with the colour running in lines to the edge of the circle until it hit the edge of the plate. The colour continued to swirl and move when we removed the swab. Interesting, but what was happening?

37

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC Understand the basics of waveparticle duality with this simple home experiment English physicist Thomas Young’s 1801 experiment into wave-particle duality provided the base for the entire wave theory movement, identifying the phenomenon of interference and the inseparability of the wave and particle natures of light. Young observed that when light from a single source is split into two beams (through his two slits) and then recombined, the beams’ peaks and troughs might not be in phase. This, he discovered, was because when a peak and trough coincide they cancel each other out, leaving an area devoid of light.

When two light waves meet of the same wavelength in phase (they have matching positive or negative electric fields), they will add together to form a brighter light. However, if they are out of phase, with their electric fields cancelling each other out, they will combine to produce an absence of light.

To test the theory ourselves, we just need to take a short step into the world of quantum physics…

The doubleST EP 1

Step 1. Start by taking your laser pen and taping its On button down, so that you get a consistent beam of light. By doing this you will ensure that you don’t have to tamper with the setup when it’s action time. After all, you will be firing the laser pointer through three very narrow needles, and any movement will throw off your results.

Be careful while doing this, in order to avoid shining the light into anyone’s eyes.

ST EP 3 ST EP 2

Equipment: 1 x s heet of card (black) 2 x foam cups 1 x laser pen 1 x Sellotape 1 x pen knife 1 x Blu- Tack 3 x needles

Step 2. Next, squish the laser pen into a large glob of Blu-Tack and then fix it to the bottom of an upturned foam cup. This will be your firing platform, and it should look something like this. At this point, it would be a good idea to measure the height of your pen, as you will need to position your pins at the same height.

38

Step 3. Now take your three pins and insert them side-by-side into the bottom of your second foam cup. This is harder than it sounds, as they will need to be as close together as possible but without breaking into each other’s puncture holes. If the pins branch out at their ends, space them with a small blob of Blu-Tack.

THE DOUBLE-SLIT EXPERIMENT

-slit experiment ST EP 4

ST EP 5

Co nc lu si on

Step 4. Now take a sheet of black card and bend it slightly so it curves. This will allow you to stand it on its end, where it will remain upright without clamps.

This will act as your firing board, onto which your laser pen will shine through the needle slits.

Interference

Step 5. Finally, set up your three components like this on a stable surface.

Distance between each part is important in the return of optimal results.

With a greater distance between pen, needles and card your interference pattern should have greater fringe spread (the light waves will diffract more), however if closer together you will get more intense bands of light and dark. Just experiment to see what works best for you.

ST EP 6

The light waves interfere with each other, adding together or cancelling each other out.

Radiate The light rays act as waves, radiating outwards from the centre.

Double slits

A single light source passes through two slits.

Step 6. Once you are happy with the experiment’s layout and that the laser pen is shining through the needles, kill the lights. If you have been successful in your preparation you should have something like this marking your card – narrow bands of interchanging light and no light radiating out in intensity from a central spot. If your lines are too blurry and the fringes are blending together, try moving the pen closer to the needles. If you just get an intense red dot, ensure your pins are close enough together and that your pen, needles and card are not too close.

So what have we learnt from this? If the experiment has been a success, you’ll have a single light source emanating from the laser pen that, once passing though the double needle slits, seems to generate multiple light bands on the black card, interspersed with bands of no light at all. If this is the case for you then great, as you have just demonstrated how light particles (photons) act both as particles and as waves.

The experiment has shown that when photons en masse (projected from the laser pen) pass through the two slits, they radiate outwards as waves – just like that of water waves – either combining or cancelling each other out dependent on their electric field. This explains why on the card we do not just have two narrow bands of light directly behind the two needle slits, but instead have a wide spread of light/dark bars stretching out horizontally.

Take a look at our diagram on the left for a graphical representation of how these processes work.

39

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

Split water

Conduct an electrolysis experiment to split water into hydrogen and oxygen

1

2

Fill your beaker

Take a beaker or a glass and begin to fill it with warm water. The water doesn’t need to be boiling for this experiment to show some results; however, high temperature electrolysis is being investigated as a more efficient means of producing hydrogen and DON’T oxygen, than room DO IT temperature AL ONE electrolysis. The If you’re under 18, mak e sure beaker only needs to you have an adult with you be half full.

3

Now take two standard pencils and sharpen both of them, top and bottom, so that the graphite is clearly exposed at each end. You may need to remove the erasers and metal sleeves depending on the type of pencil that you use. The graphite that is found in pencils is vital to this project, as it conducts electricity but doesn’t dissolve in water. This will allow the pencils to act as electrodes in this experiment.

4

Position the electrodes

Start splitting water

Complete the assembly by connecting each pencil to a six or nine-volt battery with an alligator clip, making sure the clips are securely clamped onto the graphite. If you don’t have any alligator clips, two pieces of wire with around 2.5 centimetres (one inch) of insulation removed from each end will suffice. If you do end up using wire, make sure you tape it in place.

Take a piece of cardboard that is big enough to lie on top of the beaker without it falling in. Pierce two holes into the centre of the cardboard and push the two pencils through the holes so that their graphite tips are fully submerged. For the experiment to work, the graphite must not be touching the bottom of the glass. Make sure the pencil holes are tight, so that the pencils won’t move.

5

Make the process sustainable

There are a number of ways you can build on the design that you have already created. To take your electrolysis experiment to the next level, you can add an electrolyte to the beaker water in the form of table salt. Check to see if more bubbles form than without the electrolyte (be careful, as small amounts of nasty chlorine gas may form). You can even make your experiment completely sustainable by using solar cells instead of a battery, for sun-powered electrolysis.

40

Prepare your pencils

In summary…

As soon as you complete your setup by connecting the pencils to the battery, you will notice that bubbles start to form around the tips of the submerged pencils. These bubbles are actually the elemental components of water (hydrogen and oxygen), which have been split by the electricity as it passes through the water between the two pencils.

SPLIT WATER/MAKE COMPOST

Make your own compost Turn your garden waste into nutritious plant food

1

2

Pick a good spot

The ideal area for your compost heap should be a patch of soil that gets plenty of direct sunlight, as heat aids the composting process. You could buy a compost bin, or section off an area using wire mesh or planks of wood. It should be about 0.9 metres (three feet) tall by 0.9 metres (three feet) wide by 0.9 metres (three feet) deep, creating an area 0.7 cubic metres (24.7 cubic feet) in size.

3

The first layer

Start your compost heap with a layer of brown material high in carbon. This could include dead leaves, branches, twigs, wood chips, coffee filters, shredded newspaper, cardboard, sawdust and hay. Make sure larger pieces of material are chopped or shredded to allow for good airflow at the bottom of the pile. You could also add a little soil or manure to help kick-start the whole composting process.

4

Add more layers

Add a layer of green material rich in nitrogen to help generate heat. This could include grass cuttings, leaves, weeds, fruit and vegetable scraps, eggshells, tea bags and coffee grounds. Break up any large clumps of green material to allow air to circulate and then repeat the process until you have alternating layers of brown and green material. The ideal mixture should be three parts brown to one part green.

Keep it moist

Between each layer, sprinkle your compost heap with a little bit of water. You should add just enough to make it damp, but not so much that it becomes too soggy, as this will drown out the microorganisms, cause the material to rot and leave you with a useless, slimy mess. In really hot weather, you could cover your compost heap with a lid or sheet to keep the moisture in.

5

Turn the mixture

Once every one or two weeks, use a pitchfork or spade to turn the decomposing mixture and introduce oxygen to the compost heap. This will encourage aerobic decomposition, speeding up the composting process. As the microorganisms break down the material, they will also produce heat, so you may notice your compost heap start to give off small amounts of steam. After about three months, the compost should be dry, crumbly and no longer giving off heat, meaning it is ready to use.

In summary‌ With the right mixture of nitrogen, carbon, air and water, microorganisms use oxygen to break down dead plant matter and create carbon dioxide, heat and compost in a process called aerobic decomposition. It’s a great way to recycle garden, some food or vegetable waste, and will keep your beautiful garden plants and flowers happy and healthy, too.

41

G N I Z A M S A T C F E O J K O R O P BO G N I L O O H HOMESC

The perfect paper p Equipment:

1 x A 4 sheet of paper 1 x ruler 2 x hands The current world record for time spent aloft by a paper plane stands at 27.6 seconds and was set by American Ken Blackburn, having held and lost the record several times previously before reclaiming it in 1998. In case you’re hoping to blow his record out of the sky, Ken hit the weights to improve his throwing power and is an aeronautical engineer, so he knows a thing or two about how to keep a plane in the sky.

We’ve chosen this variety of paper aeroplane, commonly known as the Cobra, because of its balance between ease of construction and propensity to stay aloft.

Other models require tape and scissors, but the Cobra’s elegant design and delightfully graceful flight makes it a favourite on How It Works. The Cobra already has a fairly weighty front end, but if you want to give it a real edge, try a paper clip or two on the nose.

096

Step 01

Step 02

Step 03

Fold a piece of A4 paper lengthways and then open it out again. Fold the top left and right corners into the central fold as shown above.

Fold the nose along the centre line until the tip reaches the bottom of the fold. Then open up the piece of paper right out back to its original shape.

Locate the two vertical creases at the top of the paper, about two inches from the top left and right hand corners. Pull them towards each other so that they meet while the central crease forms a triangle that folds down into the middle of the paper. The top of the paper should now form a trapezium shape.

Step 06

Step 07

Now repeat step five, but this time fold the corners behind the trapezium. You’ll need to unfold them again and turn the paper back over.

This is the tricky part: the trapezium should currently be folded down so that the paper forms a rectangular shape, as shown above. Take the top left and right corners and tuck them into the centre so that the points meet in the middle – they should collapse neatly underneath the trapezium to form step eight.

THE PERFECT PAPER PLANE

plane step-by-step!

TOP 5 PLANE MAKING TIPS 1 Ensure that the folds you make are accurate and they all line up as they should.

2 When creasing along a line, use the edge of a fingernail to make sure the fold is sharp.

3 If necessary, try a practice run first, just to get yourself familiar with the folds and how the shape progresses.

4 Use a ruler to line the edges up if you’re not able to do it accurately using just your hands.

5 For extra effect, why not use different coloured paper and make a whole air force to bombard your mates at work!

Step 04

Step 05

Fold the trapezium downwards over its bottom line so that the paper forms a rectangular shape again, as can be seen in the diagram for step five.

Take the top left and right-hand corners, fold them over into the centre so that the points meet in the middle and bottom of the trapezium fold. Then unfold again.

Step 08

Step 09

The shape of the plane should be obvious by now. Turn the paper over then fold it in half along the central crease, making sure that the flaps remain on the outside.

Fold the wings down halfway so that the edge of the wing is now parallel with the fuselage and the nose remains flat, but not shaped to a point.

TIME FOR THE TEST FLIGHT‌

Step 10 Your paper plane is ready to fly! Some suggest that this model makes a good dart, to be held flat and thrown hard. In practice though, we found it to be an excellent and accurate glider: find a slight rise, hold it parallel to the ground and use your arm more than your wrist to gently push it airborne.

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