After many years of sitting through undergraduate lectures, I’m ready to give my definitive criteria for what makes a good lecturer. I’ve never lectured, but I know what I like!
My three criteria are these: confidence, enthusiasm and empathy …
1. Confidence
Nothing ruins a lecture faster than the thought: this person doesn’t know what they’re talking about. We’ve all experienced the frustration of being taught the wrong thing, and then having to go back and relearn something. Lecture courses take a lot of work: notes, exercises, summaries. I want to know that my hard work will be rewarded, that when I am confused, it is just me. If I just keep working and thinking, the fog will clear. If the lecturer lacks confidence, it sends the message that my confusion may just be a result of the lecturer’s confusion. The fog may never clear, because the fog is in the mind of the teacher. I might as well get a good textbook and teach myself.
The classic example is the botched derivation. The lecturer goes to the blackboard, starts scribbling a few things, becomes flustered, erases half the board, and tries to start again. I’m not talking about minor algebraic problems, such as a lingering minus sign. I’m talking about when the lecturer doesn’t appear to know the broad outline of the derivation – where to start, what direction to go, where it ends up. They waste our time, and erode our confidence. If I’m going to have to figure it out myself, then why should I listen to you at all?
So know your stuff, and show us that you know your stuff. If you get stumped, then come back at the start of the next lecture with a clear, concise answer.
2. Enthusiasm
Students (especially at university) usually come to a given subject with a keenness to learn. Nothing saps that enthusiasm faster than a lecturer whose tone and body language send the message that they find this subject tiresome. It doesn’t take much to show enthusiasm. I remember one of my lecturers, having taken us through Einstein’s A and B coefficients, making a comment about how “gorgeous” this physics was, and that any physicist would have given their right leg to have discovered these equations. That was enough to keep me focused for the rest of the course.
One sentence is enough. “Today were going to be looking at … This is really good stuff.” If you have done any research relevant to the lecture, give yourself a brief plug. I loved that as a student. I remember a complex analysis lecturer saying: “this problem remained unsolved until 1993 when it was knocked over by yours truly!” It shows that this isn’t simply something that someone has forced you to teach. You’re actually interested in this subject.
A little bit of interest goes a long way when it comes to a student’s work ethic. A lecturer’s enthusiasm will rub off on the students, so let it show. Be aware of your body language and tone: talk as if what you’re saying is interesting!
3. Empathy
I arrived in Cambridge keen to attend some of the Part III lectures in the maths department. Part III is a legendary mathematics course, taught by some truly great scientists. Some of the courses were excellent – John Stewart on general relativity was a delight. One of the courses, however, was possibly the worst I have ever attended. The lecturer was confident and somewhat enthusiastic, yet had no empathy for his audience. It was obvious that he saw the lecture as an opportunity for him to demonstrate his knowledge. Whether or not we understood him was beside the point. His confidence became smugness – he knew how to do a derivation, so it didn’t matter that he couldn’t quite remember the details. He would just face the black board, mumble a few things, scribble a few (tiny) equations, and then just forget about it and go back to his horrendous transparencies. He thought that because he knew his stuff, he didn’t need to prepare too much for his lectures, to carefully arrange his material, to prepare well set-out transparencies, to revise the derivations, to find out what was unfamiliar to us and thus needed extra explanation. He would dismiss questions with trite answers, or proof by intimidation: “it’s trivial”.
My Year 12 maths teacher, on the other hand, was no great mathematician. He occasionally reminded us how difficult some of this was for him. His great strength as a teacher was knowing what his students would find difficult. He knew when to slow down. He knew when to explain something in several different ways, and with several examples. So ask yourself this question: which parts of this lecture will the students find difficult? Can I explain this in other ways?
A good example of empathy in action is giving your audience verbal markers: “this is important”, “you already know this”, “this is subtle”, “the big idea is …”, “note carefully how I’m phrasing this”, “this is the tricky bit in the derivation”. Plan “bring back” points, where you do something different to recapture your audience’s attention. Show a video, do an experiment, tell a brief (and somehow related) anecdote, say: “we’re halfway – let’s recap”. Talk to your audience, not at them or to yourself.
Empathy with your audience will also lead to a careful consideration of the use of jargon (including acronyms). Here’s a great example from Martin Rees, in a summary talk to a conference:
Once the first black holes form, we need to ask how efficiently they grow. And the growth by accretion is what gives you conspicuous effects. The particular issue is what happens if a black hole is smothered: if the material rains down on it in a super-critical way? Does that material get swallowed or blown away?
He doesn’t go straight for the technical term: super-critical supply. He begins with a much more intuitive terms: “smothered”, “rains down”. It creates a much clearer mental picture, and is much easier to listen to. Leave as much technical detail and jargon as possible in the published paper or textbook. (Just once, I’d like to hear a talk from an observer that included the words “I won’t bore you with the details”). Don’t make something simple sound complicated.
My point can be summarised by a comment that was once made about Richard Feynmann: “he is the only one who ever explained quantum mechanics to me as if I could understand it”. Read that quote through a few times.
In summary: show that you know what you’re talking about, show that you find it interesting, and show that you care whether or not we know what your talking about.
More in this series:
Public Speaking for Scientists:
Letters to Nature 
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