Science

Phet Interactive Simulations
Includes all science topics such as Biology, Chemistry, Physics, Earth Science, etc.

Science (Khan Academy)

Science News

Science News for Students
Founded in 2003, Science News for Students is an award-winning online publication dedicated to providing age-appropriate, topical science news to learners, parents and educators. Published daily, SNS posts both shorter news stories and longer features, all written with a vocabulary and sentence structure aimed at readers 9 to 14 years old. The stories highlight ongoing research in fields ranging from astronomy to zoology.

BioInteractive
Cool site that includes activities such as animations and simulations!  Key in your topic at the search box, get results, and then limit by video or simulation. 

The Biology Project

Biology4Kids
Basic biology and life sciences information.

Dictionary of Biology
Biology terms and definitions plus audio pronunciation!

DNA From the Beginning
An animated tutorial on DNA, genes and heredity.

Merlot's Virtual Labs engage you in learning through active participation. 

Be sure and Explore Virtual labs in Biology that offers interactive, inquiry-based biology simulations and exercises. 

Chemistry Experiments (Saddleback College)

50 Awesome Chemistry Videos
Check out the first section of experiments!

Virtual Chemistry Lab
Mix chemicals virtually without wearing safety goggles!

Chemistry/Biochemistry Labs  (University of Nebraska-Lincoln)