Yellowstone National Park Just for Kids (http://www.nps.gov/yell/forkids/index.htm)

Whether you're planning a vacation trip to Yellowstone National Park, or just want to learn about this area of extreme natural beauty, this site is sure to please. It's a good way to get an overview of Yellowstone's history and natural features, without being overwhelmed by information. There's also a link to a sister Yellowstone site called "Windows into Wonderland," which offers terrific online field trips, investigations, and up-close looks into intriguing geological processes, unusual wildlife, and ecological challenges facing the park.

For a look around other U.S. National Parks, kids ages 6 to 13 and up should hightail it to the Web Ranger link. There you can try some outstanding interactives, including learning how to pack a dog sled, sort recyclables from trash, guide sea turtles to the ocean, and how to strategically place forts in order to guard a harbor.