Harcourt Science book web site http://www.harcourtschool.com/index.html
plants http://www.mcwdn.org/Plants/PlantsMain.html
More plants interactive site http://mbgnet.mobot.org/bioplants/main.html
Plants http://www.urbanext.uiuc.edu/gpe/
Sound http://www.sci.mus.mn.us/sound/topcss.html
Trees http://www.urbanext.uiuc.edu/trees2/
Rock Cycle animation http://www.childrensmuseum.org/geomysteries/faq1.html
Rocks and Minerals http://www.mnh.si.edu/earth/main_frames.html