Conduction

Heat energy passes through solids by conduction.

When we give heat energy to a solid its temperature rises. The particles in the solid vibrate more vigorously. Because the particles in a solid are very close together and joined together the energy is passed on from particle to particle. So the energy passes through the solid from where the temperature is high to where it is low.

Metals are good conductors. Non-metals are poor conductors. They are good insulators.

This pan is made of metal. The handle is made of plastic. Why?	The tiles under the space shuttle are fantastic insulators. They need to be on re-entry.	This immersion heater is made of metal. Lots of heat gets into the water quickly.	Imagine taking this hot pot out of the oven without a good pair of oven gloves.

Liquids and gases are very poor conductors of heat.

In liquids the particles are not joined together very strongly so the energy is not passes on from particle to particle very well.

In gases the particles are too far apart to pass on energy very well.

Why are metals very good conductors?

One reason is that they have "free electrons".

Tiny particles in-between the particles are free to move around. They can bang into each other passing energy along the solid. Non-metals do not have free electrons. (free electrons are also why metals are good conductors of electricity)