Website
PBS

Pbs Nova: The Mysterious Life of Caves

For Students 9th - 10th
Companion to a PBS program in the Nova series. There are wonderful photos of the Lechuguilla cave system in New Mexico, and some new information on how caves are formed.
Article
Other

Missouri Conservationist Online: Missouri Cave Life

For Students 9th - 10th
Excellent article describing a trip inside a cave. The article discusses the cave habitat and changes that occur as you go deeper into the cave. Includes interesting photographs.