Quiz

How Things Work

Rainbows, floating boats, and why the sky is blue. Eight questions about the everyday world — with the reason behind every answer.

Ages 6–108 questions

1.Why does the sky look blue on a sunny day?
- A. The sky reflects the blue sea
- B. Sunlight scatters, and blue light scatters the most
- C. The air is painted blue
Reveal the answer
Sunlight scatters, and blue light scatters the mostSunlight is made of every colour mixed together. When it hits the tiny gases in the air, blue light bounces around far more than the other colours, so blue reaches your eyes from all over the sky.
Sunlight is made of every colour mixed together. When it hits the tiny gases in the air, blue light bounces around far more than the other colours, so blue reaches your eyes from all over the sky.
2.A big metal ship weighs thousands of tonnes. Why does it float?
- A. It pushes aside enough water to hold its weight up
- B. Metal is lighter than water
- C. The engines push it upwards
Reveal the answer
It pushes aside enough water to hold its weight upA ship is mostly hollow, full of air. It shoves a huge amount of water out of the way, and that water pushes back hard enough to hold the ship up. Squash the same metal into a solid ball and it sinks.
A ship is mostly hollow, full of air. It shoves a huge amount of water out of the way, and that water pushes back hard enough to hold the ship up. Squash the same metal into a solid ball and it sinks.
3.What makes a rainbow appear?
- A. Clouds mixing their colours
- B. The Sun changing colour after rain
- C. Sunlight bending and splitting inside raindrops
Reveal the answer
Sunlight bending and splitting inside raindropsEach raindrop works like a tiny prism. Sunlight bends as it enters, splits into its colours, and bounces back out — which is why you only see a rainbow with the Sun behind you and rain in front.
Each raindrop works like a tiny prism. Sunlight bends as it enters, splits into its colours, and bounces back out — which is why you only see a rainbow with the Sun behind you and rain in front.
4.Why do you hear thunder AFTER you see lightning?
- A. Sound travels much slower than light
- B. Thunder happens a moment later
- C. Your ears are slower than your eyes
Reveal the answer
Sound travels much slower than lightThey happen at the same instant. Light reaches you almost immediately, but sound crawls along at about 340 metres a second — so counting the seconds tells you roughly how far away the storm is.
They happen at the same instant. Light reaches you almost immediately, but sound crawls along at about 340 metres a second — so counting the seconds tells you roughly how far away the storm is.
5.What keeps you stuck to the ground instead of floating away?
- A. Air pressing down on you
- B. Gravity
- C. The weight of your shoes
Reveal the answer
GravityGravity is the pull between anything that has mass. The Earth is enormous, so its pull is strong enough to hold you, the oceans, and the atmosphere in place.
Gravity is the pull between anything that has mass. The Earth is enormous, so its pull is strong enough to hold you, the oceans, and the atmosphere in place.
6.Why does ice float on top of your drink?
- A. Ice is lighter than water for its size
- B. Bubbles push it up
- C. Cold things always rise
Reveal the answer
Ice is lighter than water for its sizeWater is unusual: when it freezes, the molecules lock into a pattern that takes up MORE space. The same amount of stuff spread over more room means ice is less dense, so it floats.
Water is unusual: when it freezes, the molecules lock into a pattern that takes up MORE space. The same amount of stuff spread over more room means ice is less dense, so it floats.
7.How does a plant make its own food?
- A. It eats soil through its roots
- B. It uses sunlight, water and air to make sugar
- C. It absorbs food from the rain
Reveal the answer
It uses sunlight, water and air to make sugarThis is photosynthesis. Leaves capture sunlight and combine water from the roots with carbon dioxide from the air to build sugar — and they release the oxygen we breathe as a by-product.
This is photosynthesis. Leaves capture sunlight and combine water from the roots with carbon dioxide from the air to build sugar — and they release the oxygen we breathe as a by-product.
8.Why does a bicycle stay upright while it is moving?
- A. The spinning wheels resist tipping, and you steer to correct
- B. The frame is too heavy to fall
- C. Air holds the bike up
Reveal the answer
The spinning wheels resist tipping, and you steer to correctSpinning wheels resist changing direction, but the bigger secret is you: when the bike leans, you steer slightly into the lean without thinking about it, which brings the wheels back underneath you.
Spinning wheels resist changing direction, but the bigger secret is you: when the bike leans, you steer slightly into the lean without thinking about it, which brings the wheels back underneath you.

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