The NASA PlanetQuest activity, "Why do we put telescopes in space", demonstrates how the Earth's atmosphere affects how we do ground-based astronomy and the advantages of putting telescopes in space.
From Bob Havner, amateur astronomer in San Jose: "I did the activity with my Project Astro class and the kids had a great time with it! Rather than using a small marble in a box as the planet I used a basket ball with Scooby Doo and Ghost pictures on it. This made it very easy to demonstrate to a large class ( 31 4th & 5th graders ) and still made for a good example. Each student had their own "telescope" and I gave them Star & Planet stickers to decorate their scopes. "