Jeez, I never had a physics instructor like this!
A roomful of lucky students at Plymouth University (UK) are about to learn from Dr. Roy Lowry the difference between gas and liquid physical states, and the energy transfer that occurs as an element shifts from one state to another.
All it takes is a plastic water bottle half-filled with liquid nitrogen, a protective plastic bucket with some warm water, and 1,500 ping pong balls. Watch and learn.
(My first thought when I saw this was: “Dang, I had access to liquid nitrogen at my last job! Why didn’t any of us do this at a party??”)