Chemistry & Physics

Chemicool Periodic Table
http://wild-turkey.mit.edu/Chemicool/

Chem4Kids
This site that is full of chemistry concept areas that include sound clips, interactive quizzes, information about famous scientists and their discoveries. In addition, there are specialty areas of chemistry such as electrochemistry, nuclear chemistry and organic chemistry. A fun, great way to learn chemistry.
http://www.chem4kids.com

MathMol Hypermedia Textbook for Elementary School
Tutorial on molecules and atoms, elements, compounds, and mixtures.
http://www.nyu.edu/pages/mathmol/textbook/5gradecover.html