www.chem4kids.com : An easy to understand chemistry site.
www.mathleague.com : Quick answers to math problems for students grades 4 - 8, including these categories: Fraction, Geometry, Integers, and Introduction to Algebra. Although this site's main interest is math contests for kids grades 4 - 12, it also has practice tests, web links, tutorial files and home schooling resources.
www.nasa.gov : National Aeronautics-Space Association's website (NASA). Space exploration updates as well as planet and other space related information.
www.usgs.gov : U.S. Geological Survey web site. Teaches everything from glacier movement, landslides and even mapping.
www.nws.noaa.gov : Web site of the National Weather Service, the government agency in charge of helping people prepare for all types of weather occurrences.