Every girl scout knows to use kindling to get the campfire started. Here’s why the small scraps work better than big logs of wood.
Fire is a reaction between molecules–mostly molecules of oxygen in the air and molecules of carbon in the wood. You can speed up reactions in different ways–say by providing more oxygen by blowing on the recalcitrant fire. But one of the easiest ways is by increasing the surface area of one of the reactants—in this case, the wood.
The only part of that big log that can burn is the outside. And most of the wood is on the inside.
By breaking that log up into little sticks, you increase the number of molecules that are exposed to oxygen, and thus increase the rate of reaction.
So gather s’more kindling to get those marshmallows roasting!