The cycle of energy is important to many different systems on Earth. Scholars use questioning and observation to investigate the differences between renewable and non-renewable resources and how they relate to global changes. They...

Useful introduction to the carbon cycle with a diagram and a discussion of the effects of carbon dioxide on the greenhouse effect and global warming.

Understand the role that the carbon cycle plays in the ecosystem.

Discover how mass extinctions play a part in Earth's life history.

Learn about some sources of outdoor air pollution.