Bitesize Science - http://www.bbc.co.uk/bitesize/ks2/science/
BrainPop - http://www.brainpop.com/
MacMillan McGraw Hill Text book (newer version) - http://www.macmillanmh.com/science/2008/student/
National Gallery for America's Young Inventors - http://nmoe.org/gallery/inductees.htm
Inventions Made by Kids - http://inventors.about.com/od/kidinventions/