"On Effective Lecturing"
In This Section
by Isaac D. Abella
I have been asked to lecture about the process of lecturing, rather than on a subject in my discipline. Since I have not done this previously, and I have not been very self-conscious on this issue, I will be somewhat intuitive and autobiographical. At the outset, let me note that the bipolar themes here of Lecturing and Discussion are really the extremes of a continuous spectrum of possibilities. My own classes are mainly lecture format, but I also try to get the class involved in some conversation. On the other hand, I have observed discussions that often have an extensive lecturing component.
The lecture format is useful in physical sciences largely due to the informational and expository nature of the subject. Conversation helps to discover lack of clarity or to correct misunderstandings, but it is rare to discuss or read texts in a manner familiar to humanities students. Nevertheless, some new modes of teaching sciences do involve discussion and cooperative learning, which may improve the way the subject is taught at the introductory levels.
It is unfortunate that most physical scientists are poorly trained in the teaching profession, at least formally. The first opportunity that I had, fresh out of college, to stand up in front of a class was as a Graduate Student Tutor (a.k.a. Teaching Assistant) at Columbia. It was a lab section, mostly show and tell, where we supervised the lab experiments, then talked one-on-one with students about their lab work, offering explanations when necessary. Our training consisted mainly of doing the lab prior to the class, so that success in a laboratory section depended more on one's ability to engage students one at a time in conversation, a cocktail party skill, than on any lecturing ability. I suppose this is where lecturing and discussion ultimately converge, when only two persons are involved. Ideally, we should have one teacher for each student.
In physics, the formal "teaching" starts when you are asked to give a 15 minute contributed paper at a Physical Society Meeting on your thesis research-in-progress. Sometimes you attend a previous meeting to listen and to observe the mode of these talks. If you are lucky, your professor/advisor will ask you first to give a dry-run talk to the other graduate students in the group, so the presentation can be critiqued: a better opening statement of the problem, things to add or omit, items to leave unexplained as too obvious or too difficult, or items to explain in detail even if they are obvious or difficult. You may even get help in writing the abstract to be published in the Conference Program.
My own first experience with this process was a 30-minute invited paper in a new and hot field. Our group of 4 authors had submitted a paper to be published in a journal. I was selected to deliver a conference talk prior to publication, armed with a manuscript in hand and the figures prepared as slides. All I did was read the paper verbatim, calling out "next slide" at appropriate points marked in the manuscript.
It turned out to be the worst talk I have ever given. I had lost eye contact with the audience and couldn't see their reaction: the talk was too stilted and boring. I could have delivered this by telephone. Over the years, I have developed a more personal style and it is my task here to give some of the details of what it is I do. I will call them "rules" for brevity, but this should not be taken seriously.
My first rule of effective lecturing, is for the student to observe your professors at work lecturing in your classes or seminars. At the end you say to yourself: "that was really a wonderful talk", or "a terrible lecture, waste of time". Why was this good or bad? Try to analyze what elements stimulated your interest, or what was boring or disorganized about the lecture you just heard. This is your opportunity to let others try, risk-free, all the major mistakes. I have unashamedly copied other people's best ideas, and tried to avoid the deadly or sleep-producing features. To summarize rule #1: steal the best ideas from the role models that you have available.
I can still remember the first time I heard or observed certain stylistic features of lectures that pleased me as a student that I continue to emulate and make part of my own repertoire. For example, as part of every lecture, I do something which students tell me they appreciate, which I first observed in a graduate course at Columbia, in Prof. Jacques Luttinger's solid state physics class more than 30 years ago.
He would spend the first two minutes of each class reviewing the highlights of the previous lecture. This helped set the context for the lecture to follow, and was essential if you missed the talk. Then he would take two minutes more to write an outline on the board of what he was to cover in that class, a kind of annotated road map. This set up an anticipatory agenda, so that in the middle of a highly mathematical exposition or derivation one already knew the result and the reason for doing this heavy analysis. It was a justification for the temporary "eye-glaze" syndrome which sometimes occurred.
This practice stands in stark contrast to some lectures I have attended and continue to attend that offer poor introductions or lack motivation. They start from an obscure place, and head in a direction that seems pointless and boring, so that I am unwilling to invest more time in it. That would be a sign of ineffective lecturing.
Of course, there are the obvious mechanical things which I assume everyone who has listened to a lecture knows about. I don't even give this a rule number, perhaps we should call it the zero'th rule: talk loud, write big and bold and legibly, face the class, seek eye contact, summarize periodically to keep the pace to human scale. How often have we listened to a lecturer who mumbled, looked down at the notebook or on the floor, never looked at the class, faced the board so he couldn't see a student raise a hand for a question, wrote faintly in tiny script, in Tibetan. Next time, I will send that person a copy of this talk.
An ineffective form of lecturing in my opinion is one which relies on the overhead projector and where nothing gets written on the board. Transparencies get whipped on and off in rapid succession which cannot be absorbed in the allotted time or have too many lines of text that are invisible from the front row. Sometimes I have seen two overhead projectors running simultaneously on side screens for the people with four eyes. I rarely use overhead transparencies to give a classroom lecture (I do use them at professional meetings) because there is a tendency to cram in too much material, which cannot be read and written down fast enough by humans using a pen. The lecturer could correct some of these problems by distributing xeroxed copies of the transparencies in advance.
This leads naturally to the issue of lecture preparation. My rule 2 is: Be Prepared, a famous motto. Overhead transparencies do require preparation and I have seen a few examples of excellent seminars using them. Michael Turner in Astronomy gave a physics colloquium recently on Cosmology and Dark Matter which was the best use of transparencies I have seen in many years. This is the exception that proves the rule.
By preparation I mean, I never walk into a lecture that I have not written out completely in longhand, with detailed derivations and with more than enough material so I can occupy the allotted time. If I teach the course a second time, say next year, I always re-write the lecture, revising it along the way. The most deadening practice, I think, is to use old, yellowed lecture notes, about which one has long since forgotten the details, and to copy them onto the blackboard. I repeat here an anecdote told to me by my Physics colleague Bruce Winstein about a class he took as an undergraduate. The professor, following his custom, was copying his yellowing notes on the board and after the lecture, Bruce went up to the front to ask a question about some detail. The professor looked puzzled, then leafed through his notes carefully several times, then finally replied "I'm sorry, it doesn't say."
Actually, the worst offender is the one who walks in unprepared without notes, ready to wing it from memory, and most of the time this results in numerous errors and false starts, lack of coherence and student discouragement. Very few people that I know can do this successfully.
However, preparing and writing out the lecture does not mean reading it in class. In my practice, I leave the notebook open, but rarely refer to it. Since the material is fresh in my mind, I write in impromptu fashion on the board, and turn to my notes only to refresh my memory on a fine detail if I get stuck. This way I can address the class more often and can detect either nodding assent or puzzlement on faces, or hands raised.
Rule number three: make your lectures worthwhile enough for students to come and listen to them. Students tend to be busy and tired, would rather stay in bed in the morning after working to 3 AM.
How do we arrive at what is worthwhile to talk about, given the prescribed syllabus? In my view, the students must feel that they can't get this material anywhere else in the same way. Students often say they can miss this or that class because it's all in the book anyway and reading the book is more efficient. Once they have the impression that the class can be missed without much loss, you have eliminated the most important thing: the audience. My response is to give them a reason to be present. This translates into: don't copy the text book onto the board or don't use a single source for the material. The lecturer's role is to know the field well and the variety of materials available, so a synthesis can be made which is valuable enough for the student to choose to attend. Some of the instructor's own work and contribution must be visible. In my case, I often decline to use an explanation or derivation given by the course text, but seek out another one to give a different viewpoint.
In organizing the topics to be covered, I think it is important to treat each lecture as a verbal short story, yes, even in quantum physics. I have a theme or story to tell, the ideas are characters, they go somewhere or do something, and there is a punch line or a climactic scene, some interesting result, application or proof, and the agenda is a thread that connects logically from beginning to end. Digressions or issues that don't help the story move forward are to be avoided. Questions en route from students that clarify or enhance the story are welcomed, those that anticipate some idea downstream, I acknowledge by saying "you're ahead of my story, hang on", and those that are far off the mark I say, "see me after class". This idea of the story-line approach can surely be applied to all the disciplines.
In undergraduate physics, I take much time and effort to set up lecture demonstrations and simple experiments in class, which help enhance the lecture with concrete examples. The instructional benefit of lecture demonstrations is remarkable since they provide evidence for abstract principles. In each of my lectures, I try to show several experiments which accompany the lecture material. Some lecture demonstrations from my own college physics days are still vivid for their clarity and elegance, and bring to mind the underlying concepts. It ought to be possible to have similar examples in other disciplines. In graduate courses, this show and tell method is not used very much.
The 4th rule is to lecture at an appropriate level for the students enrolled as specified in some syllabus or department announcements. Know (or find out) what your students know, so you can connect smoothly to their level of preparation. The best lecturer in the world can fall flat if the subject level is so far over the heads of the group that panic sets in, or is so far below the level as to be insulting. I know of colleagues who invariably teach the same 2nd year graduate level course, (or phy sci course) independent of what actual population is in the classroom. This leads to frustration and hostility, or boredom. That does not mean one needs to water material down to avoid difficult subjects, so that the material lacks integrity. If you intend to talk about subject C and students understand subject A, then you need to discuss briefly subject B in enough detail to get to subject C. There cannot be logical or informational gaps, otherwise you lose your group. Furthermore, one tendency that needs to curbed is lecturing to the top student in the class. There will always be a spread in class preparation, so my rule: "Know what the students know" also requires understanding the heterogeneity of the group.
Finally, rule 5, the most important thing about giving a lecture is to be excited and visibly interested in the material at hand. If you are not excited and are bored by the subject, the students pick this up at once. I cannot tell you how to get excited about your subject, but if you are not, you are in the wrong field, so switch now. Enthusiasm is infectious and if you have it and show it, your students will be enthusiastic and interested as well.
To some extent, this positive attitude may be personality dependent. On the other hand, there are some distinguished research faculty members who have personality traits that are more reserved, withdrawn, and misanthropic. I read an obituary recently about a senior research professor in another university, who was famous for responding to knocks on his office door with his standard shout: "Go away." Such individuals ought not to teach classes except for research seminars in their own specialty. I am sure that some of these attributes could have been overcome earlier in their careers with proper guidance and instruction, such as the Chicago Teaching Program.
I hope this discussion has helped you think about these issues.
Department of Physics, University of Chicago