Kids Discover: Free lesson plans and other resources
Cool Math 4 Kids: Puzzles, quizzes, games, geometry, jigsaws, brain teasers, fractions, coloring pages, and more
Science Monster: Tour Mars, land a space craft on the moon, see giant robot moths, and more
Funbrain: See it all for yourself - too much to do and see to tell it here.
Storyline Online: Features professional actors reading notable children's books and extending supplemental activities for each book. This site is provided by the Screen Actors Guild Foundation.