This site provides two interactive exercises designed to help the user learn about river processes like discharge, flooding and flood frequency. Both exercises require the user to make observations and measurements, do simple calculations, and answer questions. Full description.

Virtual Earthquake is an interactive computer program designed to introduce you to the concepts of how an earthquake epicenter is located and how the richter magnitude of an earthquake is determined. The program operates by showing you a seismogram detected by instruments far away from the earthquake. You are to locate the epicenter of an earthquake by making simple measurments on three seismograms ... Full description.

This site is a description of the ozone depletion problem with maps, movies and computer simulations of the Antarctic ozone hole. It has a history section, a section on current ozone loss, a detailed section on the chemistry of the stratosphere, and a description of the latest research. Full description.