Fun Science

What Makes a Rainbow?

• A rainbow is one of the most beautiful things you can see in the sky.
• It appears when sunlight shines through raindrops. Each raindrop bends the light and splits it into colours.
• The colours always appear in the same order: red, orange, yellow, green, blue, indigo and violet.
• You can only see a rainbow when the Sun is behind you and the rain is in front of you.
• Every rainbow is a full circle, but we usually only see the top half because the ground is in the way!

Why Do Leaves Go Green?

• Leaves are green because of a special substance called chlorophyll.
• Chlorophyll helps plants make food from sunlight, water and air. This process is called photosynthesis.
• In autumn, some trees stop making chlorophyll. The green colour fades and you can see yellow and orange colours that were there all along.
• Without green plants, there would be no oxygen for us to breathe. Plants are very important for life on Earth.

How Do Volcanoes Work?

• Deep under the ground, the rock is so hot that it melts into a thick liquid called magma.
• When pressure builds up, the magma pushes upwards and breaks through the surface. This is called a volcanic eruption.
• When magma comes out of the ground, it is called lava. It flows out very hot and then cools and turns solid.
• Over time, the cooled lava builds up into a mountain shape. That is how volcanic mountains are made.
• Volcanoes can be found on land and deep under the sea.

What Is Gravity?

• Gravity is an invisible force that pulls things towards each other.
• The Earth is very large, so its gravity is strong. It pulls everything towards the ground — that is why things fall down.
• Gravity is what keeps the Moon going around the Earth, and the Earth going around the Sun.
• If there were no gravity, you would float away! That is what happens to astronauts in space.
• You can feel gravity every time you jump. The reason you come back down is gravity pulling you.

The Water Cycle

• Water on Earth is always moving. It never disappears — it just changes form.
• The Sun heats water in rivers, lakes and seas. The water turns into an invisible gas called water vapour and rises into the sky. This is called evaporation.
• High up, the air is cooler. The vapour turns back into tiny water drops. These drops group together to make clouds. This is called condensation.
• When the drops get too heavy, they fall as rain, snow or hail. This is called precipitation.
• The water flows back into rivers and seas, and the cycle starts all over again.

Amazing Animal Senses

• Animals can sense things in ways that humans cannot.
• Bats use sound to find their way in the dark. They make high squeaks and listen for the echoes. This is called echolocation.
• Sharks can sense tiny amounts of electricity given off by other animals in the water.
• Bees can see colours that humans cannot see, including ultraviolet light. Some flowers have special patterns that only bees can see.
• Dogs can smell things up to 100,000 times better than humans. That is why they are so good at finding things.

Floating Egg

Materials

• A glass
• Water
• An egg
• 6 spoons of salt

Steps

1. Fill the glass about two-thirds full with water.
2. Gently place the egg in the water. Watch it sink to the bottom.
3. Take the egg out. Stir in the 6 spoons of salt until it dissolves.
4. Put the egg back in. Watch what happens this time!

Rainbow in a Glass

Materials

• A glass
• Water
• A small mirror
• A torch (or sunlight)

Steps

1. Fill the glass with water.
2. Lean the small mirror against the inside of the glass, partly underwater.
3. Shine the torch onto the mirror in a dark room.
4. Look at the light that bounces onto a wall or piece of paper.

Dancing Raisins

Materials

• A clear glass
• Fizzy water (or lemonade)
• 5–6 raisins

Steps

1. Pour the fizzy water into the glass until it is about three-quarters full.
2. Drop the raisins in one at a time.
3. Watch closely for a minute or two.

Make a Compass

Materials

• A needle
• A small magnet
• A bowl of water
• A piece of cork or a leaf

Steps

1. Rub the needle with the magnet about 30 times, always in the same direction.
2. Place the cork or leaf on the water so it floats.
3. Carefully lay the needle on top of the cork or leaf.
4. Watch which way the needle points.

Balloon Rocket

Materials

• A balloon
• A long piece of string
• A straw
• Tape

Steps

1. Thread the string through the straw and tie the string across a room.
2. Blow up the balloon and pinch the end so no air escapes.
3. Tape the balloon to the straw, then let go of the end.

Coloured Celery

Materials

• A stick of celery with leaves
• A glass
• Water
• Food colouring

Steps

1. Add about 10 drops of food colouring to a glass of water.
2. Cut the bottom off the celery stick.
3. Stand the celery in the coloured water.
4. Wait 24 hours and check the leaves.

• A rainbow is made when sunlight bends through raindrops. — Each raindrop acts like a tiny glass prism. The light bends and splits into all the colours you can see — red, orange, yellow, green, blue, indigo and violet.
• Honey never goes off. — Honey has very little water and a tiny amount of natural acid. This means bacteria cannot grow in it. Pots of honey found in ancient Egyptian tombs were still good to eat after thousands of years!
• Octopuses have three hearts. — Two hearts pump blood through the gills to pick up oxygen. The third heart pumps blood around the rest of the body. When an octopus swims, its third heart stops beating, which is why they prefer to crawl.
• Light from the Sun takes about 8 minutes to reach Earth. — The Sun is very far away — about 150 million kilometres. Light travels extremely fast, but even at that speed it takes roughly 8 minutes and 20 seconds to reach us.
• A bolt of lightning is hotter than the surface of the Sun. — Lightning can heat the air around it to about 30,000 degrees Celsius. The surface of the Sun is about 5,500 degrees Celsius. That is why lightning is so dangerous.
• Water can boil and freeze at the same time. — This happens at a special point called the triple point, where the temperature and pressure are just right. Water can exist as a solid, liquid and gas all at once.
• Snails can sleep for up to three years. — If the weather is too dry or too cold, snails cover themselves with a thin layer of mucus and go into a deep sleep until conditions improve.
• Your heart beats about 100,000 times every day. — That adds up to about 35 million beats in a year. Your heart pumps blood around your body all day and all night without stopping.
• The Earth is not perfectly round. — Earth is slightly wider at the equator than it is tall from top to bottom. It is shaped a bit like a ball that has been gently squashed.
• A blue whale's heart is as big as a small car. — The blue whale is the largest animal that has ever lived. Its heart can weigh about 180 kilograms and beats only about twice per minute when the whale dives.
• Plants make their own food using sunlight. — This process is called photosynthesis. Plants take in water through their roots and carbon dioxide from the air, then use sunlight to turn them into sugar for energy.
• Sound travels faster through water than through air. — In air, sound travels at about 343 metres per second. In water, it travels at about 1,500 metres per second — more than four times faster!
• A day on Venus is longer than a year on Venus. — Venus spins very slowly on its axis — one turn takes 243 Earth days. But it goes around the Sun in only 225 Earth days.
• Butterflies taste with their feet. — Butterflies have tiny taste sensors on their feet. When they land on a flower, they can tell if it has nectar just by standing on it.
• The human body has about 206 bones. — Babies are born with about 300 bones, but many of them join together as you grow. By the time you are an adult, you have around 206 bones.

Visit the interactive Science page for a new fact every day and a quiz.