Aaron Keller, Chemistry teacher, demonstrates the amazing properties of liquid nitrogen. He explains each demonstration in an understandable way. The temperature of liquid nitrogen is -196C (-321F). He explains how a dewar flask works. He pulls balloons out of a cooler, showing the expansion of a gas as it warms. He demonstrates the explosive power of the expansion of liquid nitrogen in an enclosed container. Liquid nitrogen is so cold that the floor is like a hot griddle. Liquid nitrogen has a very low viscosity. He demonstrates how brittle a flower becomes when frozen in a liquid nitrogen bath. Finally, he shows how to shatter a racquetball. As a bonus he shows how nitrogen gas can be used to put out a candle flame.