The theme of structure as it developed at the Woods Hole conference refers to the importance of presenting the basic structures of the disciplines as the focal points of curricula. Basic structures consist of essential concepts, such as “supply and demand” in economics or “conflict” in history or “energy” in physics, and the relationships among them. Such concepts, when understood, enable students to understand many of the phenomena in that discipline and similar phenomena that may be encountered elsewhere. As Bruner wrote, “Learning should not only take us somewhere; it should allow us later to go further more easily...The more fundamental or basic is the idea, the greater will be its breadth of applicability to new problems” (pp 17-18). Bruner advocated that these fundamental ideas, once identified, should be constantly revisited and reexamined so that understanding deepens over time. This notion of revisiting and reexamining fundamental ideas over time is what has become known as a “spiral curriculum.” As time goes by, students return again and again to the basic concepts, building on them, making them more complex, and understanding them more fully.