I’m taking a graduate statistical mechanics course this semester. My first physics course in more than two years, and my first graduate physics course.
One reason I started disliking physics courses when I was an undergraduate was that class time was spent almost entirely on going through the details of the derivations in the textbook. If there’s anything guaranteed to send me to sleep, especially if it’s a 9.30am class, it’s someone at the board moving symbols here and there and reciting the arithmetical rules he’s using to move those symbols. Furthermore, the vast majority of derivations are mathematically straightforward and can be understood from a close reading of the textbook. I don’t need someone to go through what I can glean from reading the textbook on my own.
For whatever reason, I thought that graduate classes in physics would be better. Well, this one isn’t. The professor is going through nearly every single line in Pathria’s text. What’s more, he actually tells us to read the textbook beforehand because he doesn’t want us to be looking at the textbook figuring out the math while he’s “teaching”. But if I read the textbook beforehand (which I do), I understand the derivation, so I get bored when he comes to class and goes through the exact same derivation, except more slowly and in more painful detail. So far I’ve always ended up working on my problem sets during class instead, which I find a much more productive use of my time.
One point that Eriz Mazur makes in this excellent talk on science education is that in a humanities class, it’s standard to expect students to do the assigned reading. The class then proceeds with the assumption that students have done the reading. The instructor does not hold your hand and lead you through every line of the reading. It is also understood that if you don’t do the readings, it pointless to go to class because the class is going to assume you’ve at least grappled with them, and start off on that higher level.
The opposite happens in science classes. In the vast majority of physics classes I had, even if the professor recommends that you read certain parts of the textbook or lecture notes, s/he still leads you by the hand through the very material that you’ve just read. You could not read any of it and still get the contents of what you were supposed to have read through the lecture alone. (The one class I had that did not follow this mould, which was also my favourite class in any subject ever, was taught by someone who would receive negative feedback from most students about his more Socratic teaching style. People complained that he did not follow a textbook, but for me, it is exactly when someone follows a textbook that his lectures fail to add value.) The learning style encouraged by such teaching seems to be passive rather than active, compared to humanities classes.
All this may be excusable as a sop to undergraduates who are either too stupid or lazy to read textbooks on their own, but firstly, the same undergraduates are not treated as such by their humanities instructors, and secondly, why is this still going on in graduate classes? Why do graduate students have to be hand-held through a textbook? If you can’t read a textbook like Pathria on your own, should you even be in a physics PhD programme?
A useful contrast is with my philosophy graduate seminars. There, as with undergraduate humanities classes, you’re expected to do the readings before class. Discussions in class proceed on the assumption that you have done your readings. Students are typically asked to present some of the readings, and the presentations will have some sort of summary of the contents of the readings, but it’s nothing to the extent of the presenter going through step by step of the arguments in the readings, the way physics teachers go through the textbook derivations step by step. And of course, there is much discussion of the readings.
I discussed this with someone before, and the response was that in science, there is typically a definite “right answer” to questions, whereas in the humanities, most of the important answers are still unknown. The implication is that if there is a “right answer”, then this should be told to the students. In contrast, if the right answer is not known, then discussion might somehow bring one closer to it.
I suspect many people think of science education this way, and I think they’re deeply mistaken. The objective of science education as I see it is not to tell people the right answers. The objective is understanding. People may know the right answers without understanding why they are right. In physics, the analogue would be if a student could do all the problems set by her instructor by the simple expedient of applying certain formulaic rules, but does not understand why those rules hold. This was my situation for most of my physics classes, and was a huge contributor to why I became frustrated with physics. Of course, I did go to my professors outside of class to try to get a deeper understanding, but most of the time they could not answer my “conceptual” questions. They seemed to be prepared only to tell students how to apply certain rules, without being able to justify those rules themselves.
The peer discussions that Mazur and an increasing number of people who study science education are advocating go some way to helping students get to the answer on their own and, on the way, gaining a deeper understanding of why the answer is what it is. It makes science education more like humanities education.
Pushing the idea further, I see no reason why a graduate class in physics cannot be run like a graduate class in philosophy. Have the students read the relevant section of the textbook beforehand. This should be just as obligatory as doing the readings for humanities classes is. In class, ask if anyone has had any problems understanding the assigned readings. If someone has, try to straighten her out. Do not go through every step of the proofs in class, since it could (and should) well be the case that most students understand the proofs already. Class time should be used instead to discuss interesting implications of the proofs, setting the context for them, considering the assumptions they use and what implications those assumptions have, and so on. In fact, I also see no reason why the model of having students present on the assigned readings cannot be applied. Do physics professors have such low expectations of their students that they think they cannot learn on their own and have to be spoonfed just like undergraduates? Or is it I who has overly high expectations of physics graduate students?