Useful links for your challenge projects
http://science.nasa.gov/default.htm - Science @ NASA Headline news
http://www.livescience.com/ - LiveScience
http://www.sciencenewsforkids.org/ - Science news for Kids
http://medmyst.rice.edu/ - infectious disease games!
http://learn.genetics.utah.edu/ - a good source of information on genetics topics
http://www.worsleyschool.net/science/scilinks.html - tons of science links from a school in northern Canada
http://www.sciencedaily.com/ summaries of research news in science
http://news.bbc.co.uk/2/hi/science/nature/default.stm BBC science pages
http://www.cnn.com/TECH/index.html CNN Science/technology
http://www.cyanova.com/news/science.html Cyanova links to articles in many magazines
http://www.sciam.com/section.cfm?id=news Scientific American
http://www.scienceagogo.com/ Science a Go Go!
immune system game