National Park Service
The Secret of Life
Dead trees provide nutrients for the soil, food for animals, protection and a home for organisms, a seed-bed for new trees, and a place for nitrogen-fixing bacteria to live. In the activity, pupils collect decaying logs, expose them to a...
NASA
Erosion and Landslides
A professional-quality PowerPoint, which includes links to footage of actual landslides in action, opens this moving lesson. Viewers learn what conditions lead to erosion and land giving way. They simulate landslides with a variety of...