Combustion needs a steady supply of oxygen to keep a substance burning. In this setup, you place a peanut inside a large metal can with air holes that acts as a chimney. Those holes let oxygen reach the peanut so it keeps burning.

Calorimetry measures heat energy stored inside a substance by burning it and tracking the temperature change. You stick a peanut on a needle pushed into a cork and burn it beneath a can of water. The temperature rise in the water reveals how much energy the peanut contained.

Energy conversion also works in reverse: stored chemical energy can change into heat energy. A peanut holds stored chemical energy. When you burn it, that chemical energy converts into heat that warms a can of water above it. The temperature rise tells you roughly how much energy the peanut released.

A peanut holds stored energy that comes out when it burns. You push a needle into a cork, stick a peanut on the needle, and position a small can of water above it. Before lighting the peanut, you record the water temperature. After it burns out, you stir the water and record the new temperature. The rise tells you how much energy the peanut released — and you can calculate that result in British thermal units.