1. Chloe, 10½, asks: why does the wind blow side to side and not up and down?

   1. Because the clouds tell it which way to go

   2. Because Earth spins, and warm and cool air move sideways – though wind does blow up and down, too

   3. Gravity pulls all wind flat

   4. Because birds flap their wings sideways

2. Isaac, 8, asks: what was the world’s population 1,000 years ago?

   1. About 120 people

   2. About 200 million to 300 million – the same number as in just Indonesia today

   3. More than 7 billion – nearly the same as today

   4. Way more than today

3. Emily, 5, asks: why can we see through water?

   1. It’s magic!

   2. It’s made of liquid glass

   3. Water lets light pass through it

   4. Fish clean it thoroughly

4. Joni, 4, asks: how are mountains formed?

   1. They grow from seeds, like trees

   2. Giant rock structures in the Earth’s surface push against each other and the ground is slowly forced up to form a mountain

   3. Meteorites fall and pile up into a mountain

   4. People built them thousands of years ago

5. Elsa, 7, asks: why does food turn into poo?

   1. So that you can make the bathroom really stinky

   2. It’s how your body gets rid of what it doesn’t need from the food you eat

   3. It’s made by little poo goblins in your tummy

   4. We have no idea!

Solutions

1:B - Wind blows from side to side because of the Earth’s spin and the movement of air. When warm air flows over a warm surface, it rises, and cooler air flows in to take its place. This flow of air is the wind. Wind also moves up and down – like in storms and tornadoes. , 2:B - We estimate that 1,000 years ago, there were from 200 million to 300 million people on Earth. That’s the same as today’s population of Indonesia or Mexico., 3:C - We can see through water because light travels through it without being scattered or stopped. If water is full of bubbles or dirt, it’s harder to see through because light gets blocked or bounced around., 4:B - The Earth’s outer layer is made up of rock structures called tectonic plates that move very slowly. When two plates push against each other, they force up the ground. Over a very long time, this forms a mountain., 5:B - When you eat food, your body breaks it down, and the useful parts – like protein and carbohydrates – go into your blood to help you grow, move and think. The bits your body doesn’t need (like fibre) come out as poo!

Scores

1. 5 and above.

2. 4 and above.

3. 3 and above.

4. 2 and above.

5. 0 and above.

6. 1 and above.