A favorite demonstration is to boil water by lowering the pressure in a bell jar using a vacuum pump. Unfortunately, purchasing a bell jar, vacuum plate, and vacuum pump can run upwards of $1,000 which poses a hardship for many teachers. Here are two simple and inexpensive demonstrations of phase equilibrium and vapor pressure.
Face to face professional development provides the opportunity for teachers to learn from and share with other teachers. This post provides an example of one of the many great ideas that I have learned from other teachers.