This software provides interactive, visual simulations of molecules and atoms in real time, in both two and three dimensions, using molecular dynamics methods. The simulations cover topics such as classical mechanics, mechanical engineering, electrostatics, energy conservation, gas laws, diffusion, and many others. Users may also use the authoring system to create their own interactive models and model-driven activities. Site materials include instructions for downloading the software, a collection of simulations, screenshots illustrating the software's features, and a frequently-asked-questions feature.