How I Teach
Andrew J. Berger, The Institute of Optics

I learned I had been selected for this award while in my office, checking my messages after being away on vacation. I was completely shocked, because when you return from vacation, none of the messages waiting for you ever contain good news. So I fear I've now used up my lifetime quota. But it's worth it. This is a tremendous honor, and I thank my students, my department, the selection committee, and of course the Goergen family in particular for your generous and bold highlighting of undergraduate teaching. My office and labs recently moved, in fact, to the new Goergen Hall for biomedical engineering and optics, so I feel especially blessed by this family's support. Now I just need to join the gym.

We've been asked to comment on the subject of "How I Teach". Since this is a convocation, I'd like to turn that question around for the freshmen and ask, "How do you learn?" Whenever I prepare a class, I back off and think about how people learn. Specifically, I think about some ideas proposed in a book of essays called The Aims of Education, by Alfred North Whitehead, a mathematician and philosopher in the first half of the 20th century.

Whitehead proposed that a healthy educational process has three stages. First is what he called the stage of Romance. This is where you're interested in a subject and start playing around with it, finding out what you enjoy, and assembling experiences in an unstructured way. For a student entering my electromagnetic theory class for optics majors, there are many optical phenomena that might inspire Romance. "The sun looks yellow, and it's what illuminates the sky, but the sky itself looks blue. Weird!" Or, "Isn't it cool how water droplets cause light to spread out into a rainbow?" Or even, "My computer's anti-glare screen is so smart, it knows the difference between photons from the overhead lights and those coming out of my monitor!"

Once you're sufficiently romanced by a topic, you can move on, said Whitehead, to the stage of Specification. At this point, you've amassed so many experiences that it is a joy to have an instructor provide frameworks to hang them on. In electromagnetic theory, one of our Specifications is to calculate how light shakes an atom's electrons; after some work, we derive that atoms scatter blue light more powerfully than red light. So the sky being blue makes a little more sense!

Once you've mastered a lot of details, you can move on to the third stage, which Whitehead called Generalization. In electromagnetic theory, once we've figured out why the sky is blue, we push this little shaking-electron model harder, and eventually it tells us which colors of visible light should travel slower in glass, how water droplets spread light out into a spectrum, and whether blue or red will be on top in a rainbow. We experience the pleasure of using our tools to explain a wide range of phenomena.

So: Romance, Specification, and Generalization. This paradigm has affected my teaching style. Preparing each topic, I ask myself: am I taking the students through the three stages? I now spend more time on qualitative, Romantic introductions to each topic than I used to. As often as I dare, I break the class into small groups and let them argue with each other for a few minutes about introductory questions. My students feel confused at first-"Hey, it's a science class and he's not lecturing!"-but most of them eventually get into it. Consciously devoting time to Romance doesn't leave me as much time for Specification in class, but this is probably a good thing. It has forced me to isolate the critical steps of derivations for lectures and to entrust many of the details to the homework sets.

These three stages also have given me a vocabulary for what I expect of my students. When I plunge into deriving a formula for light scattering, I'm assuming that you agree it's exciting to plunge in-I'm assuming fluency with Romance. When I later point out that this formula explains a range of optical phenomena, I'm assuming that you know the proof well enough to appreciate how general it is-I'm assuming fluency with Specification. My job is to try to spend sufficient time on each stage for you to achieve fluency and make the transition to the next level.

I'm an imperfect educator, though. Your job, in all your classes, is to keep your own tabs on how you're progressing through the learning stages. In particular, don't underestimate the importance of Romance. In science and engineering, in particular, there's a temptation to believe that your education is mostly about "racking up skill after skill," or in other words, all about Specification. The biggest favor you can do for your education is to fight this way of thinking. Demand of yourself that you can always answer the question, "Why is this topic interesting to me?" Dare to focus on Romance. You need that fluency to progress.

If you can't sustain the Romance alone or with your friends, talk it over with your professor. Here's a surprise: most of us aren't experts in terms of having formal training in how to teach. But all of us are experts at loving our fields of study! So if you want to get the most out of any teacher you have at Rochester, tap into this expertise! Walk into my office and start the conversation this way: "I've been trying to figure out why I should find this class interesting, and this is the best I can do...." I promise you'll be rewarded with a spirited conversation, and it'll probably be the best learning moment in the class-for both of us.

I'll close with an anecdote. I wrote an early draft of this speech on my home computer, which is shared by my wife and children. To keep my professional items separate, I have a folder called "Andrew", and in it a folder called "Work". When I went to edit the speech one night, I was confused because I couldn't find it anywhere. At first I suspected my five-year-old, and then my two-year-old. But no, the reason was that I hadn't saved the speech in my Work folder. I'd put it in another folder called Teaching. I guess that unintentional organizing reveals how fond I am of teaching, that I don't even consider it to be Work. May all of you freshmen form similar feelings towards all of your classes here at Rochester. Thank you all again for this special recognition, and I look forward to continuing the teaching journey together. Thank you.

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