Educational Gameshttp://www.funbrain.com
A good site that describes how many different things work. It also includes games.http://www.howstuffworks.com
A good site for researching various topics.http://www.enchantedlearning.com
Fun Schoolhttp://games.funschool.com/games.php?level=6
Fact Monsterhttp://www.factmonster.com/
Quiz Hub - A fun interactive online learning center. Play games, do puzzles, and take quizes on any subject.http://quizhub.com/quiz/quizhub.cfm
Trivia Palacehttp://www.redmond.k12.or.us/patrick/renz/trivia.htm
Test Your Knowledge! Fun quizzes from Great Britain in the areas of math,science, and English.http://www.bbc.co.uk/schools/revisewise/challenge/index.shtml