Your dentist can tell a lot about your health and daily habits just by looking at your teeth. But did you know that archaeological scientists have discovered that there is a lot more information hidden in teeth? We can study the chemical composition of teeth and can find out what types of food a person ate, and even where that food was growing. When we find teeth in archaeological sites, a method called isotope analysis can be used to reconstruct the movements and diets of people, even when no written records are available. In this article, we will discuss what our teeth are made of and how isotope analysis can be used to learn more about ancient people. We will then look at an archaeological site in France, where children discovered bones and teeth on the playground behind their kindergarten.