Nature Research
Nature Education: Energy Economics in Ecosystems
This article discusses how plants and microorganisms, until recently, have mostly controlled how much carbon dioxide is released into an ecosystem, and explains how this process works. Humans' burning of fossil fuels has upset the...
PBS
Pbs Learning Media: Discovering Air
Our understanding about the air we breathe has changed dramatically through time. This illustrated timeline from the NOVA Web site tracks the changing thought on air and the creation of the Periodic Table of the Elements.