My goal when I entered Harvard College in 1954 was to get a degree in science, probably chemistry, go on to graduate school and ultimately teach at the college level. I thought it would be useful to get some teaching experience to find out whether I liked it and would enjoy this career. So I volunteered through Phillips Brooks House to tutor chemistry and algebra at the North End Union, an historic settlement house in Boston’s North End. My tutees were a group of young men from a local Catholic high school who attended my tutorial session for a couple of hours each week, so they could “earn” a like amount of time playing basketball in the Union’s gymnasium. I thought then and still think the director was a genius for her creative use of incentives to help the local youth improve their opportunities for productive adult lives.Sometime near the beginning of the second semester, the chemistry topic was equilibria involving precipitation from ionic solutions. For some reason, the students were having difficulty with the algebra involved, but I knew from our algebra work that they should have had no problem with the mathematics. When I asked what the problem was, the response from one of the students was, “What does it look like?” This was a puzzling question and when I pursued it, they wanted to know, for example, whether the entire liquid became a solid (sort of like ice). My response (as a naive graduate of a large comprehensive midwestern public high school) was, “You’ve seen this in your laboratory work.” Their rejoinder was, “What laboratory?” Lesson number one for me was never to take anything for granted, but to explore students’ backgrounds.

Lesson number one for me was never to take anything for granted, but to explore students’ backgrounds.

I returned the following week with a small box of materials I borrowed from the Harvard chemistry department stockroom – limewater, a few test tubes, and some straws. Each of my students blew gently into a test tube containing some limewater and observed the formation of the cloudy solution as a precipitate of calcium carbonate formed from the reaction of limewater with the carbon dioxide in their breath. Now they had seen what the formation of a precipitate looked like. This seemed to free them from concerns about the actual process of precipitation and, I was pleased to find, they now could successfully solve equilibrium precipitation problems. For the remainder of the semester I carried a small box of materials to my tutorial sessions, so we always did some sort of hands-on chemistry activity at each meeting, as well as thinking through the textbook problems. Lesson number two, which has followed me through my entire career, is always to introduce phenomena before theory and abstraction. Essentially all of my professional achievements in the area of pedagogy have been based on this approach, which I credit to the opportunity and experience provided by my freshman year PBH volunteer activity.