What shape is the universe and why is milk white? Try our kids’ quiz

Illustration: Hennie Haworth/The Guardian

1. Mia, 9, asks: what shape is the universe?

   1. Scientists don’t know if it is flat, spherical or saddle-shaped

   2. It is spherical like a planet

   3. Scientists don’t know if it is square or pear-shaped

   4. It is heart-shaped

2. Dottie, 4, asks: why is milk white?

   1. Because it makes your bones stronger and bones are white

   2. It is actually green but is bleached so it looks tastier

   3. The proteins in milk bunch together to make it look white

   4. It is only white when it comes from white cows

3. Jacob, 7, asks: what is in the middle of Mars?

   1. Iron, nickel and sulphur

   2. Air, that’s why it can float in space

   3. Caramel and nougat

   4. Stone, iron and bronze

4. Eliza, 10, asks: why do we float in saltwater?

   1. Because salt makes the water denser

   2. Because salt releases bubbles in the water that keep us afloat

   3. Our skin repels us from salt so we are pushed upwards

   4. We don’t – if you can, it means that you’re a really good swimmer

5. Ishan, 7, asks: how is cement made?

   1. Powder is mixed with water to make a paste

   2. By knocking houses down and grinding up their walls

   3. Materials like limestone and clay are crushed and mixed together

   4. Cement is made from the ashes of leftover bonfires

Solutions

1:A - Scientists don’t know if the universe is flat like a sheet of paper, spherical like a ball or curved like a saddle. This is a really exciting part of science because when they figure it out, they’ll be able to know if the universe is finite or infinite! If a universe is spherical, and its ends join up, it would be finite; if it’s flat, it can technically go on for ever, so it is infinite., 2:C - Casein is the main type of protein in milk. Its molecules clump together into little globules called micelles. When light hits these, all of it is reflected rather than some being absorbed, as happens with other colours. So we see all the colours in the light, which looks white to us!, 3:A - Mars has a dense core of iron, nickel and sulphur. Outside that is a rocky mantle and, on top, a crust of iron, magnesium, aluminum, calcium and potassium., 4:A - Saltwater is denser, as in more full-of-stuff, than normal water. It’s easier for us to float in because we are less dense than it is., 5:C - Cement is made by first extracting raw materials like limestone and clay from quarries, then crushing and mixing them, before heating the mixture in big ovens.

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.

Molly Oldfield hosts Everything Under the Sun, a weekly podcast answering children’s questions, out now as a book.

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