Start here: first lessons

Six first lessons for young beginners. Pick any one, or go in order. Each lesson ends with where it leads; when you like a topic, climb its ladder of 8 levels.

	Lesson	The question	Its topic
1	Why things fall down	where is "down"?	Gravity and orbits
2	Jumping on Mars	how high could you jump there?	Gravity and orbits
3	The Moon goes round	why does it not fall?	Gravity and orbits
4	Pushes make things go	what starts a thing moving?	Rockets and landing
5	The balloon rocket	how does a balloon fly?	Rockets and landing
6	Coming down gently	how do you land softly?	Rockets and landing

There are 10 topics in all: see every topic.

For parents and teachers: level 1 suits most children from about 5, level 3 from about 9, level 5 from about 12, level 7 from about 15. Every lesson works with things from home, and the answers to the questions are folded until you tap them.