Bill Nye the Science Guy (1993)

Season 2: Episode 10

Things sure are heating up at Nye Labs. Snow cones, flowers, hot dogs, people -- everything is made of molecules. No matter what they're in, solid, liquid, or gas, molecules are always moving, even if just a little bit. The speed of the molecules depends on their temperature. Cold things have slow-moving molecules, while hot things have fast-moving molecules. In fact, temperature is really a measurement of molecule speed. For a cold thing to get warm, its molecules have to speed up. Heat moves in three different ways -- conduction, convection, and radiation. Conduction is the flow of heat between two solid objects that are touching. Heat conducts from your warm fingertips into a cold can of soda. Convection is the transfer of heat with a liquid or gas. A hot bath feels warm all over not just where you're sitting.