What happens during a lecture?

A question always likely to give strong response is whether PowerPoint should be used in lectures. Those advocating its use point to a more organised lecture where the structure has been thought out in advance. Those against it say that PowerPoint makes it too easy to put too much content in lectures and accompanying handouts. I don’t have a Yes/No opinion, because I think it depends very much on the person and what they do.

While raiding the archives of Education in Chemistry (EiC), I came across some old but interesting articles on the topic of lecturing. Before I was born, Alex Johnstone wrote an article “Attention Breaks in Lectures” in EiC. In it, he outlines a study he undertook where student attention was monitored by observers in 90 chemistry lectures. Attention drops—doodling, looking around, yawning, chatting—were recorded. Interestingly, the course been taught was delivered twice in one day, so a comparison could be drawn between groups. Not surprisingly, the average performance of a group was found to correlate with the level of attention paid. The twelve lecturers giving the course varied in style. The lapses in attention were more common in lecturers that did not vary their style compared to those that did: by using activities such as models, experiments, problem-solving sessions, etc. The general pattern of lapses in attention were found to exist at the start of the lecture and about 10 – 18 minutes later, with further lapses over the duration of the lecture. Attention span dropped during the lecture, so that by the end of the lecture, attention span was 3 – 4 minutes.

When I was starting university, Johnstone wrote another article for EiC. In this article, “Lectures-a learning experience?” Johnstone stated that the average lecturer delivers approximately 5000 words in a lecture, with a student recording about 500 of these. This article reports what students chose to write down and why they felt some information was more important. The study found that students recorded about 90% of what was on the blackboard, with inaccuracies ore common with diagrams or equations. Lecturer corrections, demonstrations and examples of applications typically went unrecorded. Note-taking styles did not vary for students, even if the lecturing style or content was different.  Students themselves ranked lecturers in terms of effectiveness, and those marked “ineffective” tended to have a higher word count per lecture—they cover more, although from the perspective of the student, they make less sense.

For me, the question is a lot bigger than “To PowerPoint or not”…

  • AH Johnstone and F Percival, Attention breaks in lectures, Education in Chemistry, 1976, 13, 49-50.
  • AH Johnstone and WY Su, Lectures – a learning experience? Education in Chemistry, 1994, 31, 75-76.

One thought on “What happens during a lecture?

  1. I’ve often speculated that attention spans in lectures are roughly comparable to the length of time between ad breaks on TV. In the UK that’s typically around 15 minutes which fits with the Johnstone paper. In North America (much to my horror!) it’s a bit shorter, 10 minutes. I’ve had classes where you could time the ebb and flow of attention to those intervals, and I’ve frequently planned accordingly with various activities for ‘breaks’. If I get desperate, it’s the 2 minute ‘just have a break while I sort out my papers/get ready for the next section’!

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