This is a popular argument of the intelligent design and young-Earth creationism community: "Teach the controversy." But one good reason not to teach creationism as a “theory” is that it can’t be tested. Evolution, or more to the point, natural selection, has survived scientific tests for more than a century. As a theory of life, it has only grown stronger. If adherents to creationism reject the findings of geology and physics, for instance, which help us understand the age of the Earth, then how can we have a data-based, evidence-grounded discussion of creationism over natural selection?