Watched 'Our Friend the Atom' (Disney, 1957) with the boys. The 6 year old loved how they described an atom like a little solar system, where the nucleus is the sun and the electrons are the planets. He told his little brother he is made out of millions of tiny solar systems, the 4 year old said 'cool'. They also showed an example of how nuclear energy works with a room full of mouse traps each with 2 ping pong balls on them, and how the chain reaction starts. I wish Disney still made these type of educational cartoons, they explain concepts so well.