Aware of such research, Green circles back to the education schools, where a zealous coterie of scholars has been trying to identify and inculcate the “habits of mind” that define the disciplines. They tend to follow the work of Stanford University’s Lee Shulman, who coined the term “pedagogical content knowledge” to describe the intellectual apparatus that you need to teach a given subject. I am a full professor at a major research university, but I could not, without much preparation, teach high school chemistry. I could, of course, require my students to memorize the periodic table of elements. But I couldn’t teach the discipline, because I don’t understand its history or structure: how it developed over time, what it has discovered, what is left to know, and what counts as “knowledge” in the first place. These are hugely complicated questions, usually reserved for graduate study in the disciplines themselves. But unless you understand how a discipline actually works, you won’t be able to help anyone else understand it, either.
And that brings us to the saddest fact of all: most of our teachers don’t possess a deep working knowledge of any discipline, at least not in the way that good teaching demands. Perhaps the teachers of very small children do not need the same mastery of a discipline as their counterparts in middle and high schools. But surely they need a deep and theoretically sophisticated understanding of the ways that children learn. Even the teaching of so-called simple arithmetic turns out to be an immensely complicated endeavor, but most of our teachers do not treat it as such. Part of that failing has to do with the lack of constructive collaboration inside our schools, where teachers work almost entirely in isolation.
By contrast, many other advanced countries have institutionalized critical commentary by peers and also provide intellectual support to improve skills and learning as part of teachers’ professional practice. Japanese teachers even have a separate word for this process, jugyokenkyu, which is built into their weekly routines. All teachers have designated periods to observe each other’s classes, study curriculum, and otherwise hone their craft. But they also learn a great deal in their pre-service training, which is both more rigorous and more demanding concerning particular subject matter than anything American teacher-education students are likely to encounter.