1. How to start a fire with flint and steel.
2. What happens when you pop a falling balloon.
3. How a strawberry grows and ripens.
4. How your brain makes assumptions.
5. How a slinky falls.
While the bottom of the slinky doesn't move until the top reaches it, the centre of gravity of the object is falling all the time.
6. The transit method of detecting planets around other stars.
7. How fast we're discovering alien planets.
8. How to make a simple motor.
9. How pi relates to the circumference of a circle.
10. Pythagoras' theorem (a2+b2=c2)
11. How the clouds move on Jupiter.
12. How this species of mushroom grows and spreads its spores.
13. Propulsion.
14. What snake venom does to human blood.
15. How tadpoles grow into frogs.
16. How Earth's ice cover varies over seasons.
17. How a baby's face develops in the womb.
