Our theories of teaching demand principles of both exposition and discussion. If you look at most of the pedagogies emerging from the seminal research on student concept learning, you will find that some form of dialogue, exchange, conversation, or alternating argument – some kind of social manifestation of the understanding – is central. Therein lies the enormous pedagogical complexity that derives from this work. That complexity is the reason why, even though we know discussion is necessary, the dominant form of pedagogy is the lecture. Lecture is relatively simple, and it reduces much of the technical and economic complexities of teaching. (Shulman, 2000, pp. 132-133)
Another reason for its difficulty is that teachers typically face not a one-on-one clinical interaction, but responsibility for 30 or 35 or 40 students. What pedagogy do you as a teacher use in a classroom when you want this inside-out, outside-in process to happen and there is only one of you and so many of them? That is why group-based strategies like the varieties of cooperative learning, reciprocal teaching, learning communities, and other types of collaborative groups have become very important in this current round of school reform efforts. They are not just a fad. We are trying to determine how, in a classroom of 35, to create an environment where more than five children per hour have the experience of bringing the inside outside. Then, with the help of others, they are able to wrestle with it; they do it for one another. They need not depend on waiting for the teacher’s intervention alone. (Shulman, 2000, pp. 133-134)
This type of teaching is difficult because of its incredible complexity, which is apparent if you compare the lecture, one source of transmitting information to a large, physically passive group, with a classroom, in which students do not have the same prior theories but are trying to wrestle concurrently with complex ideas. How does a teacher manage to create that kind of situation—to hear, to monitor, to know when to intervene and when not? We sometimes hear students communicating actively, but unfortunately exchanging misconceptions. (Shulman, 2000, p. 134)