Active learning: does depth outweigh breadth?
The fox knows many things, but the hedgehog knows one big thing. (attributed to the Greek poet Archilochus)
A friend recently sent me to a NY Times article on teaching science in the universities, whose lead-in point was, of course, how often it is done poorly. The article went on to describe several innovative ways of moving away from the ‘lecture-only’ format to active learning. By a number of metrics, these new methods have increased success in raising scores and increasing comprehension.
Yet, despite the documented successes, the article decries the resistance at most universities to changing their ways. The usual culprits are listed:
- Professors don’t care about teaching.
- Even if they care, teaching is irrelevant to career advancement.
- Lecturing is easy, doing it in any other way is more work.
- Professors like to weed out students, to limit access to more interesting advanced classes.
- Universities just like to slavishly follow tradition.
- You can’t tell a tenured professor to do anything!
In other words – all the usual tropes are dragged out. In my experience all these are more false than true. But that’s not my point in this posting. When one speaks about active learning, it generally involves stopping your lecture to discuss a point more deeply. Or having the class work out some relevant problem. Or as in this article, having the professor run up and down the stairs, asking random students questions about the material. What works here is that the lecturer gets immediate feedback as to whether or not the class is getting it. And if they aren’t, then the lecturer can go over the material again (and again? and again?) until a satisfactory level of comprehension is obtained.
Obviously, if this is how the material is being taught, students will learn and comprehend it better. However, whenever I read about active learning being extolled yet again, there is one cost that is never mentioned – time! Every time you stop the class to actively learn about one topic, something else cannot be covered at all. Consider the following.
I have taught Introductory Biology at UCLA. We are on the quarter system (classes last 10 weeks), and I taught my class MWF for 50 minutes at a time. This gives me exactly 25 hours total for when I have the students in front of me. And actually less, given that I have to start a couple minutes late to let everyone find their seats, and end a couple minutes early so not to be drowned out by the masses departing early for their next class. So, what can I cover in one ‘day’ of face time?
Certainly not all of Biology! We’ve long ago recognized this and our course is better described as an introduction to evolution and ecology. But even with this truncated definition of biology, here is a non-exhaustive list of subjects that could be covered in the class:
- Mendelian genetics, plus the modern revolution in genomic biology.
- Population genetics.
- Evolution by natural selection.
- Evolution by genetic drift and other stochastic processes.
- The Tree of Life.
- A march through the taxonomic groups of animals (which may be the only time many students would be exposed to the idea that there is more out there than mammals, birds, and fish).
- A consideration of plants (again maybe the only class students will ever take that will let them know there is more in the world than trees, flowers, grass and ‘germs’).
- Ecosystem ecology
- Community ecology
- Population ecology
- Conservation biology.
- Relevant modern-day problems for biology like climate change, biodiversity loss and disease outbreaks.
- Infuse all of the above with an appreciation for quantitative methods: e.g., mathematical models and statistical analyses.
Can you get all this into 25 hours? Maybe. How about if you add in in-class active learning exercises for each topic, which doubles the amount of time you have to spend on said topic? Now a lot has to come out – you just don’t have the time to even get to mentioning it. And this is the tradeoff I never hear mentioned.
Now I could teach my version Intro Bio, by concentrating only on my one favorite topic: Natural selection. After 25 hours of lectures, Q&A, think-pair-share, workgroups, clicker questions, and discussions you can be damn well assured that my students would walk out after the quarter comprehending natural selection very well indeed and scoring excellently on tests about it. Success, right? But have I really taught them an “Introduction to Biology”?
I will say that I do like much about active learning, and do try to incorporate it into what I do. But I also know that it comes with this great tradeoff of depth for breadth. In my advanced classes, which already have a more restricted focus, I am much more willing to go make this deal. However, for at least introductory biology, I am not convinced that a better understanding of few things (via active learning) is worth the sacrifice of not being exposed to many things (via the classical lecture). Do we want our students to become foxes or hedgehogs?