To the Editor:

I would like to react to the essay "Don't Lecture Me on Lectures" by Kelly Roos, which appeared in the Fall newsletter of the APS Forum on Education. In the last few years I have seen several essays of this kind, where the writer expresses the opinion that the lecture method is not seriously flawed, despite the findings of the physics education research community. I want to highlight serious logical errors in these arguments.

To me what is striking in all of these essays is their common structure: "Physics education research has not proved that the lecture method is seriously flawed, because there is this or that problem with the research methodology or assessment instruments, etc., so one can't believe any of those measurements. I on the other hand believe that I teach really well using the lecture method, and my personal opinion about my teaching is ever so much more trustworthy and believable than any attempts to make actual measurements, to look closely at real data, or to try to make theoretical models to explain student failures."

The analogy is clear: "Physics research has not proved that classical physics is seriously flawed, because there is this or that problem with the research methodology, etc. I on the other hand think that classical physics is ever so much better than relativistic quantum physics, and my personal opinion is ever so much more trustworthy and believable."

Despite my attempt to make cheap debating points, I do agree that it is entirely sensible to question the methods and results of physics education research, just as we should question the methods and results of any other kind of research. Indeed, physics education research is comparatively new, and it studies issues that are much more complex than those studied in other areas of physics, because people are involved. So it is not only reasonable but important that physics education research be continually subjected to careful scrutiny. But the inadequacies and possible mistakes of physics education research are at least subject to debate and scrutiny. In contrast, mere assertions that "I know better" cannot be examined further and lead nowhere.

There was one somewhat novel element in Roos's version of these essays. He says, "Whether the debunkers are right or wrong concerning lecturing, one thing is certain as we gaze across the physics teaching landscape today: the debunking hasn't worked, at least in the sense that the larger physics community has not adopted the anti-lecture stance." This and related comments are presented almost as though they were additional evidence in favor of the lecture method. But just because many respected scientists argued for many years against the existence of atoms didn't mean that atoms don't exist!

My main purpose in writing this letter was to address the serious logical flaws in the arguments presented against the findings of physics education research. But I'll add my own thoughts on the issues raised. The clearest signal from work in the cognitive psychology community as well as in the physics education research community is that students must be actively engaged with the material rather than merely observing passively. For that reason, a pure lecture method is likely to work poorly, at least in introductory courses involving students who are not yet very skilled learners.

This doesn't mean that all aspects of lecturing per se are worthless. Some particularly valuable benefits of lectures include emphasizing which aspects are more important than other aspects, and providing motivation, as happens when one shows enthusiasm for the subject. Moreover, there are ways to mitigate the passiveness of the lecture experience, and Eric Mazur's simple method for improving lectures is a good example (and one which has been adopted rather widely precisely because it requires very little change in the running of a course on the part of busy physics researchers; see "Peer Instruction" by Eric Mazur, Prentice-Hall 1997).

Bruce Sherwood, Research Professor of Physics, North Carolina State University