Just upstairs from an exhibit on African culture at the American Museum of Natural History, Robert V. Steiner sits in front of his laptop computer and clicks on an "interactive animation" that illustrates the concept of frames of reference. On the screen, a glowing basketball bounces up and down against a black background. After watching…

The co-authors have been co-Principal Investigators on two large-scale National Science Foundation-funded teacher enhancement projects for the past eight years. One of the projects focused on middle and high schools and the second focused on the elementary school. The design of each was different, reflecting the differing natures of the…