We stumbled upon a great find today when we were learning about electric circuits. The University of Colorado in Boulder has a great website chock full of interactive science simulations. They are simple to download and use. Here is the one we discovered today:
You will find different simulations for all areas of science. Elementary, middle school, high school, and college level simulations are all available on their site. Be sure to check it out here. This site has made my boys quite happy!