Now, after having read his most recent article about teaching physics to students, I have my answer.
The article describes his views on efforts to make physics "more fun" in the class room, and all the new technology in trying to teach it.
In the US there is a movement inspired by physics education research (PER) to promote "active engagement" in the classroom. I applaud this – though it is hard for me to imagine any good teacher since Socrates who is not already practising it. But taken to extremes it can be destructive. When it is claimed, for example, that students learn nothing from lectures (because, apparently, they are not "actively engaged") I demur. It goes without saying that there are bad lectures, but there are also very good ones, in which students are totally engaged. Nobody's mind wandered during Coleman's lectures. In despair over the ineffectiveness and unpopularity of traditional methods, some PER people advocate "learning by discovery" in the lab. It is a nice idea, but stultifying slow and inefficient – how are we to rediscover 500 years of physics in a semester? I can explain the conservation of momentum in 15 minutes, but three hours in the lab would only convince an honest student that the law is false.
The Harvard University physicist Eric Mazur and others have introduced flash cards (now – inevitably – replaced by electronic "clickers") to enforce student engagement at lectures. They can be powerfully effective in the hands of an inspired expert like Mazur, but I have seen them reduced to distracting gimmicks by less-capable instructors. What concerns me, however, is the unspoken message reliance on such devices may convey: (1) this stuff is boring; and (2) I cannot rely on you to pay attention. Now, point (2) may be valid, but point (1) is so utterly and perniciously false that one should, in my view, avoid anything that is even remotely open to such an interpretation.
I quite agree with that view. I've mentioned many of these "teaching technologies" before on here, and I've always wondered to what extent these things are effective, and whether someone ELSE could conduct such a thing with the same result. My view has always been that, more often than not, it totally depends on the instructor and his/her enthusiasm, with or without such technology.
Still, that argument applies to Griffiths' article too.
I have been lucky. I spent most of my career at an institution where the students are reasonably bright and extraordinarily motivated, where effective teaching is genuinely encouraged and appreciated, and where I have enjoyed the freedom to pursue whatever strikes me as interesting and important. I have never suffered the interference of a brainless dean concerned only with grants and publications, and as a consequence I have been more productive than would have been possible in the usual academic straitjacket. I do not know what makes good teaching, beyond the obvious things: absolute command of the subject; organization; preparation (I write out every lecture verbatim the night before, though I never bring my notes to the lecture hall); clarity; enthusiasm; and a story-teller's instinct for structure, pacing and drama. I personally never use transparencies or PowerPoint – these things are fine for scientific talks, but not in the classroom. I want my students to know that something is happening in real time: I am thinking through each argument as I present it, not merely reciting something they might just as well have read in a book.
In an ideal world, we would have teachers like Griffiths and Coleman. But in reality, we don't. In fact, we'd be lucky if have half of the physics instructors we encounter in college are as interesting and enthusiastic about teaching as these two. As with the new technologies and new "tricks" that seem to be effective and could be due to the enthusiasm of the instructors themselves, so do the "old style" teaching methods of Griffiths that definitely needs someone with the same level of caliber and enthusiasm. Maybe the new technologies and new "tricks" of teaching physics to students are there to compensate for those instructors who don't have such skill and do not posses such enthusiasm. I don't know.
I do know, however, that we are never lucky enough to get outstanding teachers most of the time. What we do get, are average, even mediocre instructors, most of the time,with a few brilliant ones sprinkled along the way.