Which term describes the direct transfer of heat from one substance to another that it is touching?

The correct term that describes the direct transfer of heat from one substance to another that it is touching is conduction. Conduction occurs through the collision of particles within a solid material or between solids in direct contact. When one substance is heated, its particles vibrate more vigorously, and this increased energy is transferred to neighboring, cooler particles upon contact, resulting in a flow of heat.

In contrast, convection refers to heat transfer involving the movement of fluid (liquid or gas) where warmer parts of the fluid rise and cooler parts sink, creating a current. Radiation is the transfer of heat through electromagnetic waves, which does not require direct contact between objects. Insulation is a material property that slows down the transfer of heat, which is not a mechanism of heat transfer itself but rather a way to reduce conduction, convection, or radiation. Understanding the context of each term clarifies why conduction is the correct choice for describing direct heat transfer through contact.