Here's why:

* Metals are good conductors: Iron is a metal, and metals are known for their ability to transfer heat energy easily. This is why we use metal pots and pans for cooking – they transfer heat from the stovetop to the food quickly and efficiently.

* Heat transfer in a skillet: When you heat an iron skillet, the heat energy travels through the metal from the bottom (where it's heated) to the top (where the food is). This allows the food to cook evenly.

In contrast, insulators are materials that resist the flow of heat. Examples of insulators include wood, plastic, and rubber.