Imagine trying to teach reading to students who do not know the alphabet or driving to someone who does not know the purpose of the brake. As teachers, we have a view of what the fundamental ideas that our field are and make decisions about their coverage and order in our courses. Yet, research shows that students rarely have the foundation that we expect; they hold misconceptions about the physical world that actually inhibit the learning of many scientific concepts. Moreover, the metaphors that we employ for building student understanding: reliving the historical development of the field, journeying from the closest to farthest reaches of the universe, and observing the objects in the sky, are only based on our own beliefs in their effectiveness. Empirical evidence shows that they are of little value; there is rarely any lasting change in students’ conceptual understanding in science.