While interviewing me for my first teaching job, at a high school in California, Ernie the Principal took me to visit the classroom of Art, the teacher I would be replacing if I were offered the job.

Ernie told me that it was impossible to predict what would happen in Art’s classroom, and made it clear that he considered that a very good thing. When we entered the room, three students were at the blackboard arguing about details of photosynthesis, the rest of the class was fully engaged in the discussion, and Art was lying on a bench along the window, apparently asleep.

Ernie and I stood at the back of the room while the argument raged with no sign of life from Art. After a while the discussion took a turn, as arguments tend to do, toward the personal: “That’s stupid!” one student exclaimed, and several others responded in kind. Art stretched, then rolled slowly and theatrically over onto his side on the bench, propping his head up with his forearm. He remarked that, whereas at the beginning of the discussion everyone had listened carefully to everyone else, he didn’t think anyone was anymore: “You might learn more by helping each other, instead of trying to prove how much you know.” Then he rolled back into his napping position. Ernie winked at me and we left the room.

Back in his office, Ernie told me that although Art was the best teacher he had ever met, he had seldom caught him actually “teaching” in all the years he had worked there. He also said that, more than any other teacher he knew, Art was always trying new things, some of which flopped badly. I never actually met Art, but for over 40 years I have considered him my hero, and one of my most important mentors.
During those few minutes in Art’s classroom, I learned one of the most valuable lessons of my entire teaching career: the less I teach them, the more they learn.

Teaching in the same room the following fall, I realized how difficult it was to keep quiet and allow my students to explore ideas on their own, without my needing to “profess” to them. Eventually, I recognized that it was easier to keep my mouth shut when my hands were busy, so I began to carve small sculptures in chalk. At the end of the discussion, as we debriefed and I congratulated the class on a job well done, I presented a tiny sculpture to a student who had contributed significantly.

After a month or so of doing this, the ritual had clearly become much more than a simple trick to help me keep my mouth shut. It was a symbol and a trigger for an important component of our classroom culture that became more effective the more we practiced it (the more the students practiced talking with each other and the more I practiced staying out of their way). It was as if the simple act of my taking out my pocket knife impelled my students to enter deeply into discussion, perhaps a little like Pavlov’s dog salivating when Pavlov rang the bell.

Nowadays, we know that interactive engagement among students is the most significant factor in the development of conceptual understanding, at least by undergraduate science students. Given the apparently universal compulsion of professors to profess, I think it follows that teachers must discover ways to remain silent in their classrooms. Various manifestations of my trick of carving chalk served me well for many decades. I used my knife to slowly peel the skins from pieces of fruit and eat them, contemplatively, and I sketched students and colleagues.

Later, as a university professor, I took small stone sculptures with me to classes, meetings, and PhD exams and sanded them quietly and unobtrusively. And I found that meetings with obsessive note-takers were much more effective when conducted outside – walking briskly – thus my office hours became opportunities to exercise. These physical activities have helped me make room for my students to think and speak. And these activities sharpen my listening so that when I do speak, it is far more effective.