You can watch The Magic School Bus: Out of This World and The Magic School Bus: Lost in Space, then utilize this printable and lesson idea (scale it to a homeschooling level) from Scholastic. Here's their "Space Chase" game, as well, which gives kids clues for guessing a planet. There are also two clever poems for kids about space on this page.
Here's another huge list of space links for kids, too, and some activities from enchantedlearning.com. NASA also has a few lesson plans categorized by age.
These lesson plans are for those of you who really want to do something big: Using items like pumpkins, softballs, and poppy seeds to get an idea of the scale of our galaxy.
This site also had some wonderful application ideas from teachers on the solar system, including making marks on your playground (yard) outside to demonstrate distance between planets.