Physion is a 2D Physics simulation software. It can be used to easily create a wide range of interactive physics simulations and educational experiments. Teachers may find it particularly useful since it can be used as a virtual physics laboratory through which they can demonstrate some basic physics concepts in the classroom. The program is free and is available on Windows and Linux platforms currently, but is promised for OSX in the near future. The program is similar to Phun, but has a more robust interface and seems easier to use.