(Sample link) NASA for middle-school students http://www.nasa.gov/audience/forstudents/5-8/features/index.html
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
NASA home page http://www.nasa.gov
Animal Cells http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AnimalCells.html
Cells Alive! http://www.cellsalive.com/
NOAA's Coral Reef http://www.coralreef.noaa.gov/
Cell Division http://www.loci.wisc.edu/outreach/bioclips/CD.html
Nature News Service http://www.nature.com/news/index.html
The Virtual Cell http://www.ibiblio.org/virtualcell/index.htm
M2K4: Roaming the Red Planet http://www.nasa.gov/externalflash/m2k4/index1.html
The Nine Planets http://nineplanets.org/
WebElements Periodic Table http://webelements.com/webelements/scholar/index.html
The Comic Book Periodic Table of the Elements http://www.uky.edu/Projects/Chemcomics/
USGS Learning Web Search Results http://interactive2.usgs.gov/learningweb/lwscripts/search_results.asp
Welcome to USGS Learning Web http://www.usgs.gov/education/