The problems of teaching have now become a domain of active, systematic research by
psychologists, anthropologists, linguists, sociologists, educational practitioners, and
disciplinary specialists. What did not exist 30 years ago has become a vigorous and active
field of research. Our theories of teaching demand principles of both exposition and
discussion. Most of the pedagogies emerging from the seminal research on student concept
learning reveal that some form of dialogue, exchange, conversation, or alternating argument …