Heat - Thermal conductivity
The hypothesis that copper wire is the best thermal conductor and steel wire is the worst among the 3 types of wire, is proven to be true.
The concept of thermal conductivity can be applied to produce better cookware for cooking food and boiling water. When a pot is placed on a stove, thermal energy is transferred from the fire to the metal pot and eventually to the food and water. Materials with poor thermal conductivity can be used as thermal insulators.
Try to repeat the experiment using different metals like brass, nickel or zinc.
The experiment can also be repeated using different lengths and diameters of wire.
Thermal conductivity - http://en.wikipedia.org/wiki/Thermal_conductivity
Thermal conductivity of metals - http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
What is thermal conduction? - http://www.wisegeek.com/what-is-thermal-conduction.htm
Handle boiling water very carefully – adult assistance is required.