National Institute of Open Schooling
Environmental Concerns
Every year, more than 14 billion pounds of garbage is dumped into the oceans of the world, most of which is plastic and toxic to ocean life. Lesson 32 in the series of 36 focuses on environmental concerns, specifically pollution. Under...
CK-12 Foundation
Ck 12: Earth Science: Biological Communities Study Guide
Review the relationship between populations and ecosystems.
Other
Food Chains and Webs
A very informative site that discusses food chains and webs in detail. Not too complicated and fairly easy to understand, it also includes some pictures.