How much material do you plan to cover throughout the semester?
That’s actually a trick question. Because the answer, in my view, should be none, zilch, zero, zip, nada. If faculty members are teaching to “cover material,” are we really teaching? When we say we covered material in class, we are implicitly saying that we merely talked about it.
In the sciences, where I’ve taught biology for more than 20 years, this is a perennial dilemma — one usually framed as a matter of “depth versus breadth.” In that trade-off, the idea is that you have a set amount of information that you can cover, and the issue is whether you share a lot of information about many different topics, or you share an equivalent amount of information on a smaller number of topics. Depth-versus-breadth can be a useful concept, but it doesn’t influence teaching effectiveness or how well students learn throughout the semester.
I’m suggesting we replace that trade-off with a different dichotomy: covering versus teaching. You will always have the same number of hours in a semester, but when you cover material, you share a greater number of concepts and facts. When you teach material, you end up covering fewer nuggets of information, but the students learn them more deeply.
To use an extreme example, imagine you’re giving a hourlong lesson on some scientific theory. You could lecture for the whole hour — with a large number of slides and plenty of equations, principles, examples, and demonstrations — and share hundreds of concepts and facts. At the other extreme, in the span of the same hour, you could give your class a single problem related to that theory, and ask students to solve it in groups through discussion and inquiry. Which approach do you think will result in more genuine learning?
Let’s consider another scenario. Imagine your goal is to teach just one relatively narrow topic for an entire semester — say, a whole semester on the mammalian kidney, which would be an absurdly narrow topic at the undergraduate level. At the end of the semester, you should have a high level of confidence that the students in the class understand kidneys. After all, you spent a lot of time thinking, discussing, writing, drawing, and solving problems about kidneys. Now, imagine the opposite: Your goal is to cover “Animal and Plant Biodiversity,” including the structure and function of major anatomical features. That would include the mammalian kidney, for a minuscule fraction of the course.
If you were to compare the two courses, which do you think would result in a greater sum of more genuine learning? Imagine tracking down students who had taken both classes, two years after the final exam, and evaluating how much they’d learned in each course. It’s a safe bet that the students in the “Mammalian Kidney” course would remember more about the kidney than the students in “Animal and Plant Biodiversity” would recall about biodiversity.
Why? Because the biodiversity course covered a lot of ground, and it wouldn’t be possible to teach everything in that class in a way that would result in deep learning. On the other hand, the kidney course gave students the chance to think hard and critically on a regular basis. Less information was covered, but it was explored in more depth. A course about all of life — at least the way it is often taught — skims the surface of everything. Some departments call such a curriculum a “March of the Phyla.” When you’re marching through a lot of territory, you’re not going to remember it all that well.
Covering something merely for the sake of covering it is pointless. Introducing students to a concept, but not taking the time to actually support their learning it, rarely does any of them a useful service.
That leaves us with a real problem: Especially in the sciences, the undergraduate courses we teach typically are not about something as narrow as the kidney, and are often far more like the “March of the Phyla.” So how can we possibly do justice to such a broad topic if we don’t cover a lot of ground? This, I think, is one of our central challenges in science teaching: When we decide the quantity of material we are going to teach in a course, that inevitably structures how we teach it. If you have to cover a lot of ground, then it’s hard to teach in a manner that promotes genuine learning.
In curriculum, less is more. The more successful you are at paring down what you are going to teach, the more you can teach so that students can learn it deeply. I do think it’s possible to teach a wide range of ideas under a central theme, and still have depth of learning. Here’s how:
- Take care in selecting a small number of central topics that feed into the central goals of the course.
- Teach those select topics really well.
- Let a lot of the details go.
It’s really hard to let the details go because, as experts, we’ve fallen in love with those details. Our students, however, might learn a lot more if we focused on the big concepts, and then used some fun details for engagement and application. As a general principle, it might take an hour to deeply teach one fundamental fact or concept. That would mean that, over the course of a semester, you would need to pick out about 40 major facts or concepts, and let everything else go.
Let me illustrate coverage-versus-teaching with an example. A standard “March of the Phyla” course would involve a few lectures on the diversity of animal groups. (The class is never really titled “March of the Phyla”; that’s just a nickname used by old-school biologists.) The lectures would involve detailed information about all of the common groups of animals, and often the subgroups within each group, and evolutionary innovations found in each group that allow us to distinguish them from one another.
I taught that sort of course for a long time to lower-division students. I then would often see those students again in my upper-division classes. One student who was doing well in my upper-division “Behavioral Ecology” course, and had received a strong A in the “March of the Phyla,” asked me — with full sincerity — “Is a spider an invertebrate?” (It is.)
I did my best to try to not look shocked or annoyed, and asked, “Think back to ‘March of the Phyla.’ Do you think you could sort this out from what we did in this class?” And the student said something along the lines of “Oh, that was two whole years ago; we talked about so much in that class, I don’t think I could remember that kind of detail.”
I can’t fault students for not remembering something like that. After all, I had hit them with a tsunami of information and expected them to learn it all. After the semester was over, there was only wreckage left. To be fair to myself, this cover-it-all strategy was standard practice in the sciences, and it was expected of me by my department, but it still wasn’t the best way to help my students learn.
What could be the alternative? How could I possibly encapsulate all of the breadth of life in just 40 fundamental facts and ideas? That sounds impossible! That’s because it is. What’s even more impossible is coming up with 3,000 facts, cramming them into 40 hours of lecture, and expecting anybody to genuinely learn all of it.
Instead of packing a mountain of information into a few lessons about the evolution of major groups of animals, l now have identified three major lessons that I want students to take home. (For the curious those three are: The evolution of structural complexity in organisms allowed them to manage physical challenges in the environment; nearly all species that have existed are now extinct; and most animals are arthropods.)
That might sound like a narrow scope of concept for an introductory course. However, my students do just as well as students in a more traditional “March of the Phyla” course on an exam for that class — even though I haven’t sought to cover everything. I hope that they might be able to retain more of what they learned, as months and years pass.
This approach to curriculum is most difficult when you are expected to design your courses around a set curriculum over which you have limited control. This might be the case if you’re teaching one of many sections and need to sync your teaching with other instructors. But if you have control over your own course, then you probably aren’t as bound to a standard curriculum as you might think.
For example, in chemistry, the accreditation guidelines of the American Chemical Society say: “The diversity of institutions and students requires a variety of approaches for teaching general or introductory chemistry.” The society does prescribe a number of topics and skills that students need to learn, but it’s a very short list and allows for a ton of flexibility. Ultimately, if you want to teach a smaller set of concepts with a goal to promote deeper learning, it’s OK to experiment.
Editor’s note: This essay was adapted from a chapter of the author’s new book, The Chicago Guide to College Science Teaching.
