Dr. Forrester talks about the carbon and oxygen cycle. She describes the paths they make through the ecosystem. She also lists the ways that oxygen is removed from the atmosphere and how we use it.

This lab proves that plants produce oxygen.

This is a lab video that proves that human beings exhale carbon dioxide.

This program addresses many of the cycles conducted by animals including those of migration, hibernation, and patterns relating to day and night. The cycles that affect all living things are discussed including the air we breathe and the...