Imagine you pour some hot chocolate into a mug. how does the heat spread throughout the hot chocolate?

When a molecule is heated, it gains energy that allows it to vibrate at a higher speed. When the molecules vibrating quickly bump into other molecules, they pass some of that energy on to the other molecules which in turn causes them to vibrate at a higher speed. The energy is passed on to every molecule in the hot chocolate, causing it to be equally heated.

Show him another sport or something