Heat Transfer occurs in three ways:
Conduction - the transfer of heat through contact from warmer substance to cooler substance.
Convection - the transfer of heat in a liquid or gas due to changes in density.
Radiation - the transfer of heat as infrared light (no matter necessary to carry heat).
Recent questions that your children should be able to answer:
Why do polar bears have black skin and clear, hollow fur?
Explain how thermos bottles keep hot drinks hot and cold drinks cold.