Students used a propane torch to help them understand changes of phase (or state).
Students placed a solid, solder, into a hot flame over 350o F to change the state of the solid solder to a liquid form.
Students observed that when the solder became very hot, the molecules in the solder moved faster and farther apart.
When the melted solder cooled, the molecules got closer and moved around less. It changed back to a solid state know as solidification.
Students learned that plumbers, electrical technicians, mechanics, jewelers, and etc. use solder.
They also learned that solder is a great electrical conductor and thermal conductor.