• Three cups
  • Hot water
  • Metal knife
  • Plastic knife
  • Wooden knife (or a piece of wood similar to the size and shape of a knife)
  • Butter
  • Sugar cubes
  • Adult supervision


  1. Fill three cups with equal amounts of hot tap water.
  2. Place (handle side down) a metal knife in one cup, a plastic knife in another and a wooden knife in the third cup.
  3. Stick a pat of butter on the exposed (cutting) end of each knife. All three pats of butter must be the same size.
  4. Place a sugar cube on top of each pat of butter.
  5. Ask students to guess what will happen while they wait and watch.

Science Behind the Experiment:

The atoms in a substance are always vibrating. When heat is applied the heat energy is transferred to the atoms and they vibrate faster, causing their kinetic energy to increase. The vibrating atoms bump into other atoms and pass on their kinetic energy. These atoms then pass on their kinetic energy to atoms close to them and so on until they’ve reached the “cool” end of the object. The material that allows heat to move through it most easily and quickly is the best conductor. The butter on the best heat conduct will melt the fastest and the sugar cube will fall off. Which material was the best conductor of heat? The worst?

This activity was adapted from Summer Program, Tips, Strategies & Activities for School-Agers 5-14 Years-Old.