ABSTRACT
Many investigators in cognition and instruction agree that knowledge is acquired by construction; it is not acquired by transmission alone (e.g., Resnick, 1987). Humans acquire knowledge richer than the knowledge they are presented with, or even invent knowledge that has never been presented, often as a byproduct of such cognitive activities as problem solving (a persistent endeavor to induce desired changes in the world) and comprehension activity (a systematic attempt to offer a coherent interpretation of what the world is like). This claim is selfevident when there is no teacher or when the teacher cannot verbalize the target knowledge. However, knowledge must be constructed, at least partially, even when the teacher gives learners the target knowledge in a verbalized form, or when the teacher carefully monitors learners so that their behavior can come to approximate the model behavior. Transmitted knowledge becomes usable in a variety of tasks involving problem solving and comprehension only after it is reconstructed; that is, interpreted, enriched, and connected to the prior knowledge of the learner. Thus, learners must be active and constructive.
