One of our favorite demonstrations. Five metal spokes radiate out from a central hub. Each spoke is composed of a different metal or metal alloy: copper, iron, aluminum, stainless steel, and brass. At the end of each spoke is a small divot where you place a bead of soft wax. A paper clip is then crammed into the bead of wax. Once you have all five spokes prepared you are ready to go. Record the beginning time and heat the central hub with a flame. The heat will be conducted from the hub and down each spoke at a different rate. Record the time at which the paper clip falls off each spoke and you can make a pretty accurate statement about the ability of that metal to conduct heat.