ions, and (c) the seductive reality of the computer must not be allowed to supplant construction of models. The dominant theory of learning today is called constructivism. This theory claims that knowledge is actively constructed by the student, not passively absorbed from textbooks and lectures. Since the construction builds recursively on knowledge that the student already has, each student will construct an idiosyncratic version of knowledge. To the extent that such knowledge is not identical with “standard” scientific knowledge, the student is said to have misconceptions. Teaching techniques derived from the theory of constructivism are supposed to be more successful than traditional techniques, because they explicitly address the inevitable process of knowledge construction.