ELI5: Explain Like I'm 5

Calorimeter

A calorimeter is a tool scientists use to measure the amount of heat energy given off or taken in by an object. To measure the heat energy, scientists put the object into a sealed container called a calorimeter. This container is made so that no heat energy can escape or enter from outside the container. Scientists then measure the amount of energy released or absorbed by the object inside the container, and this helps them understand what happened.