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.
Center for Educational Technologies
Wheeling Jesuit University: How Are Things Divided Among Earth's Four Spheres?
See if you can classify various objects in the categories of land, water, air or living thing. This activity is interactive and you will receive a score for your performance.