University of Wisconsin
The Why Files: A Livable Earth Needs Air, Water, and Clouds
Make Earth's climate livable by adding the right amount of air, water, and clouds to its surface and atmosphere.
University Corporation for Atmospheric Research
Ucar: The Water Cycle
This site provides a comprehensive introduction to the water cycle. Students construct a model to simulate parts of the water cycle. Includes background information, links to standards, lesson plans, and assessment ideas.
National Earth Science Teachers Association
Windows to the Universe: Biogeochemical Cycles
Biogeochemical cycles happen when individual elements are recycled over and over in different parts of the Earth. Two examples are the Nitrogen Cycle and Carbon Cycle. Read an explanation of biogeochemical cycles and view a diagram of...
University of California
Ucmp: Creating an Earth System: Interactions in the Earth System
A brief description of the four spheres of the Earth, with an activity where students brainstorm interactions among them.
Encyclopedia of Earth
Encyclopedia of Earth: Physical Geography
Get a general grasp on the four spheres, five sub-fields, and two scales of physical geography.