Simple Machines - Learn about simple machines with this interactive website.
Water Cycle - Learn about the Water Cycle
A Walk in the Woods - Learn about the woods
Erosion - Ineractive website on Erosion
Science.gov Gateway to many government sites (topics include climate, weather, meteorology, earthquakes, floods, natural disasters, mapping and cartography, oceans and oceanography, snow, ice and permafrost, soil, water and hydrology.