While researching for some course work in Introduction to Astronomy for AMU, my six year old little boy was looking over my shoulder. So, I figured I'd explain to him that "Daddy is looking for information on asteroids for school." Well, much to my surprise, little man had heard of asteroids and even knew of asteroid belts. This lead to an interesting discussion of the Moon, Mars, blackholes, gravity and asteroids with my son – at his prompting. The kid's interest in, and knowledge of, these topics surprised me.
We followed this up with an exploration of several websites on said topics. He thoroughly enjoyed the photos of Earth, the Moon and Mars on The Nine Planets.
Information at the speed of your modem connection. Today's kids don't know how lucky they have it.