Interactive Science Lessons
Contains guided inquiry science lessons
http://www.interactivescienceteacher.com/

National Geographic - Young Explorer!
For kindergarten and first grade science.
http://www.nationalgeographic.com/ngyoungexplorer/

Peep and the Big Wide World
For introducing science to young kids.
http://peepandthebigwideworld.com/f

A Virtual Laboratory
A free virtual laboratory.
http://www.virtlab.com/main.aspx

1001 Inventions
A groundbreaking global educational initiative exploring Muslim contributions to building the foundations of Modern Civilisation
http://www.1001inventions.com/index.cfm?fuseaction=main.viewSection&intSectionID=309

Glasgow Science Center
Presents concepts of science and technology in inspiring ways
http://www.gsc.org.uk/lunarlessons.aspx

Wonderful world of science
Science topics with videos for older kids
http://www.wonderville.ca/

BBC
Science and other subjects-excellent resources
http://www.bbc.co.uk/schools/ks3bitesize/science/organisms_behaviour_health/

Eureka Science
Where learning is fun!
http://www.eurekascience.com/index.htm

Kids Health
Explains how the body works.
http://kidshealth.org/kid/htbw/htbw_main_page.html

Home Experiments
Science is fun website- free home experiments you can do with your kids.
http://www.scifun.org/HomeExpts/HOMEEXPTS.HTML

OdyseeTV
Your voice for wildlife and nature. Free programs on wildlife!
http://www.odyseetv.com/index.html

Science Class
Free Chemistry and Physics lessons
http://www.physics-chemistry-class.com