[plinkplonk]

@pg,

What do you think about the idea that good teaching involves good 'public speaking' skills and 'stage presence'? Prof Lewin of MIT for example seems to be an extremely effective teacher. People do seem to need lectures (even if in a video form) in addition to books and papers to learn maximally, even when what is being learned is science or engineering.

(I understand that teaching is about conveying existing ideas from one mind to another vs generating new ones 'at runtime'. I was just interested in what you think about the need for "public speaking" skills to be a really good teacher.)

[pg]

It's an interesting question whether lectures are necessary. I've heard universities are moving away from them. It's obvious why you want a human teaching a small class; that's a conversation, not a talk. But is there a benefit to lectures too large to be conversational besides the two that I listed (meeting the speaker and motivating people)?

It was a while ago, but I can't remember a lot of lectures from college or grad school that I found more useful than books. When I try to remember lectures that I learned things from, what comes to mind is professors writing on chalkboards, explaining things like what happened in memory when some program was running or showing what happened when you did something to a matrix. So perhaps the big advantage of lectures is that they're not just words-- that they can include visual demonstrations.

[pmjordan]

I think the effectiveness of lectures might depend on the student as much as the lecturer.

I can remember some lectures (6-10 years ago) and their content quite vividly, even if they were fairly unidirectional and to large audiences. I find that if I start looking up something that was explained in a lecture, it will trigger the memory of the lecture, even if I couldn't recall it previously. This almost never happens for things I learned from books or the internet - if I've forgotten them, I have to relearn them. It also seems to take me much longer to understand something from a written explanation.[1]

I can only assume it's to do with multi-sensory input having easier access to long-term memory. And maybe there's an emotional element, too: reading a (factual) book is an emotionally neutral experience. That's not the case when you're watching and listening to a human.

And I'm sure the effect is more pronounced in some than in others. Many other students in my year did very well despite missing lots of lectures; I think I missed about 5 of what must have been about 2000 and would have needed to do vastly more revision to pass exams. I suspect I would have dropped out of university if it hadn't been for lectures. As it turns out, I had essentially zero intrinsic passion for my subject (physics), but the good lecturers made it interesting.

[1] I realise this is anecdotal and hard to verify. The most direct comparison I can think of is this: I remember that when trying to catch up after a lecture I missed, it took me much longer than the 50 minutes to understand the covered subject matter using the blackboard notes and reference books.

[hef19898]

This week-end my father, a pretty good teacher for photography, and I, currently teaching something completely different from time to time, had an discussion on teaching. For me, the main difference between a speach a teaching is flexibility. During a speach, people are listening, but there's hardly any interaction. Teaching is more of a interaction with people. My standpoint is that teaching more or less means having people thinking about something and learn. A speach can, and should, motivate people to think about the message. But they can live pretty well without one. In order to teach well, you have to adopt to your pupils on a almost individual basis. Some have to read something to get it, others have to hear it while again others have to see or do it themselves. I guess thats why big classes tend to be that bad for learning progress.

Commin g back to topic / speaches: you have to differentiate the message from the messenger. There are alot of examples of damn good speekers with bad messages, usually with very bad out-comes.

[apu]

Two important components of lectures are

1. Tying facts and ideas together in a cohesive "story" so that it sticks better in people's minds. Good books are supposed to do this too, but sometimes you don't have the flexibility to choose the best books. Also, as in any story, you have high points and low; important bits and those less so. Emphasizing these differences and making sure students understand which are the central points is another main goal of good lectures.

2. Explaining difficult concepts in different (often multiple) ways so that people can understand them better. For various reasons, books have a tendency to avoid "intuitive" explanations for many concepts, perhaps out of a fear of not-quite-perfect analogies. Such analogies can be given in class with the appropriate qualifications; doing the same in a book would often require excessive legalese.

Where appropriate, these explanations often involve visual elements -- animations usually, and not just pictures (which you can of course include in books).