Heat conduction is when heat is transferred through molecular agitation without any movement of the object as a whole. Essentially, as a molecule heats up, it moves and shakes quickly, then moves the other nearby molecules, which move and shake in turn. Bit by bit, heat is transferred through those movin’, shakin’ molecules in a chain reaction. This may seem complicated, but it’s simple to demonstrate with this heat conduction experiment.
Start by putting a pot of water on the hot stove. Once the water is good and hot (boiling or near boiling), carefully place 3 different spoons in the pot – one metal, one plastic or rubber, and one wooden spoon.
The next step is to make a prediction about what will happen of you place a little pat of butter on each of the spoons. Have the kids write down their predictions. Here is a scientific method experiment sheet to use for this experiment.
The actual experiment happens very quickly, so make sure everyone is ready and watching when you put a pat of butter on each one.
The butter on the metal spoon almost immediately melted away; the butter on the wooden spoon melted some; meanwhile, the butter on the plastic spoon stayed firm much longer. That’s heat conduction at work. The heat was transferred by moving molecules within the spoons. The spoons themselves didn’t move, but their molecules did. This experiment also gives us some insight into what kinds of materials conduct heat well.
- Some kids may ask if cold is conducted too. The answer is no. Scientifically, cold is the absence of heat, so only heat is conducted.
- Check out this interactive website to learn about the three ways heat is transferred – conduction, convection, and radiation – and what the difference between them is.
- Why do you think the best marshmallow roasting sticks have a metal tip and a wooden handle? What would happen if your roasting stick was all metal? Can you think of other examples of materials that are used for their conduction properties?
- Is the blanket on your bed a good heat conductor? (That doesn’t mean “Does it keep you warm?” It means, “Does heat transfer through your blanket quickly and easily?” Sometimes things are useful to us because they conduct heat well, and some things are more useful to us because they don’t. What would happen if the hot pads you use to get cookies out the oven were good heat conductors?