Algebra.Help
Algebrahelp.com is a collection of lessons, calculators, and worksheets created to assist students and teachers of algebra.
Animal Diversity Web
ADW is a large searchable encyclopedia of the natural history of animals geared toward the classroom student and hosted by the University of Michigan Museum of Zoology. Every day, thousands of classroom students and informal visitors use it to answer animal questions.
Ben's Guide to U.S. Government for Kids
Useful explanations of the U.S. government.
Khan Academy
With a library of over 4,300 videos on everything from arithmetic to physics, finance, and history and hundreds of skills to practice, Khan Academy is on a mission to help you learn what you want, when you want, at your own pace.
Math.com
Math.com provides innovative ways for everyone to learn math.