Interactive - Solids, Liquids, and Intermolecular Forces
These simulations will help you understand phase changes in matter.
Activities
They say a pot watched never boils. Well, this one will, and you'll definitely want to watch it! The Phase Change Lab demonstrates the phase changes of water in a heated pot, starting from solid ice and eventually making it's way to the gaseous state, all while showing intermolecular forces and the time/temperature for you to graph out later.

Now with Concept Checkers
Special thanks to Nerd Island