Sunday, January 28, 2007

Why posting the solutions isn't the solution

Students always ask me to post the answers to the questions I give them, but I'm reluctant to do so. This makes them unhappy, as they sincerely believe that seeing the right answers is a good way to learn. But I think that seeing the answers often just gives a false sense of confidence.

Say you first try to do the problem without looking at the answer. Because you know the answer is available, you don't spend a lot of time on it. Instead you try do the problem quickly.

If you're able to come reach an answer, you don't spend a lot of time trying to decide whether the answer you've come up with is right, you just check your answer against the posted one. If it agrees with yours, you pat yourself on the back and go on to the next problem. If it doesn't, you look at how your answer differs from the correct one, say "I see how it's done; I won't make that mistake again", and go on to the next problem.

If you can't reach your own answer, you look at the posted one, say "I see how it's done; I'll be able to do it right next time" and go on to the next problem.

Using my "going to university isn't like going to the tanning salon, it's like going to the gym" analogy helps explain why this doesn't really teach you how to solve the problem. Looking at the correct answer is like watching a trainer show you the right way to do squats. You know you need to practice doing them correctly, so you do lots more squats, matching your moves to those the trainer showed you. If you just say "OK, I see" and go on to do bench presses, your squats won't improve.

But you can't go back to the same genetics problem again and learn to do it right, when you already know the answer. Working back from the answer is very much easier than working forward through the forest of possible answers. You need to build the skills that let you evaluate the candidate answers you come up with, testing each one against all the information you have.

It's comforting to think that seeing how a problem is done gives you the skills to do it. But it doesn't. Instead it gives you a false sense of security that can hold you back.

(next time - why going slow teaches you to go fast.)

Saturday, January 27, 2007


A student pointed out on the course discussion board that I'd not used colours consistently in drawing chromosomes. I apologized for the confusion and tried to clarify it in a response.

But then I raised the issue directly in class yesterday, pointing out that on Monday I'd coloured the two chromatids in a pair differently (dark ad light blue), but on Wednesday I'd coloured them the same shade of blue but coloured their homologs pink. And the transparent strips I used to demonstrate meiosis had the three different chromosomes from one parent green, whereas those from the other parent were blue.

And I then told them that I was about to use yet a different colour coding in yesterday's class, with the homologs the same colour (maternal distinguished from paternal by a wavy line drawn on them) and the different chromosomes (those with completely different genes) different colours.

The class had been given strips of coloured paper to use as their won chromosomes in solving our first genetics problems, and I told them to pay attention to the colours they used, with the goal of having the colours a guide to the relationships between the chromosomes they were representing rather than a source of confusion.

The most important thing isn't that they get the colours right, but that they learn to think about what colours will be least confusing, and more generally about how to represent the factors that matter in any given problem. It's this thinking that leads to the most learning.

Tuesday, January 23, 2007

Acting out

Yesterday in one of the two classes I teach, I had some volunteers come the front of the class and model the process I had just explained. Why is this worth doing, given that it's time-consuming and chaotic?

One reason is that it's just one more way of presenting information. Different ways work better for different people, and when a point is important I try to present it in as many ways as possible.

But there's a better reason for using students to model it. We're social animals. Almost from the day we're born, we find watching people to be more interesting than watching anything else. So, although many students will probably forget how I slid the model chromosomes around on the overhead projector, they'll remember the girls tied together at the front of the room, being tugged back and forth by boys with the yellow ropes and then released by the boy with the scissors. And maybe they'll remember that what happened to the girls is what happens to chromosomes.

Saturday, January 20, 2007

What should biology students learn?

Our Biology Program has just been awarded a big 5-year grant (from the Carl Weiman Initiative) to improve how biology is taught. One issue that came up at our first meeting was "What should we be teaching our students?"

Students reading this may be horrified to realize that this is an open question. Surely professors decide what they should teach before they start to teach it! Well, we do try, but deciding what should be taught is a complicated problem and one we have no training for.

We university professors tend to teach a combination of what we learned as students and what we've learned since. This is bad for two reasons.

First, every time we learn something new and important we're tempted to add it to the curriculum, so the amount of information we're trying to teach keeps increasing. Most of us realize this, and keep trying to cut back on the information overload, but we never go as far as we probably should.

Second, the things we learned aren't necessarily the things our students should learn, because we were far from being typical students. Many of us were uber-geeks, and we were all the kind of students who go on to be university professors. But most of our students are nothing like we were. Their futures are likely to be much more diverse than ours, and many will have no direct connection to science at all.

There's another problem. We don't feel competent to teach many of the things we would like to teach, because we have no good ways to assess whether our students have learned them. We want to teach our students how to read critically, how to think creatively, how to write clearly. We want our students to really understand complex principles and processes, not just parrot back textbook explanations. But we don't know how to assess these abilities.

The Weiman Initiative grant will give us resources to develop the assessment tools we need. But that only addresses the second problem. First we need to decide what to teach. And these decisions need to be made in collaboration with our students.

We know what biology you need to learn if you're going to be a biology professor or a high school biology teacher, and some of the biology you'll need if you become a physician, dentist, or other medical professional. But many of you will go on to careers that have nothing to do with biology. So we'd like you to tell us how you might use your biology education when you're raising a family, or working in the family business, or selling real estate, or building furniture.

You can post comments to this blog entry, or if you're in my Biology 121 classes you can post them on the course's WebCT Discussion Board.

Thursday, January 18, 2007

Finding the balance with clicker questions

Designing good clicker questions is tricky. I want them to be challenging enough that the students have to think quite a bit, but because correct answers count for marks, I want most students to get them right most of the time.

Usually I let the students discuss each question with each other before they answer. One way to improve both the benefits of the consultations, and the proportion of the answers that are correct, might be to first present the question not for marks, asking students to answer without consulting their neighbours. Then show them the range of answers (?) without indicating which is correct. Then ask them to consult their neighbours before answering again, this time for marks.

I have a couple of little books about using clickers in the classroom (gifts from the textbook rep). One is specifically about science teaching - I'll see what suggestions it has.

Friday, January 12, 2007


What we did:

1. Thought about how to infer properties of ancestors, when we know the properties of the descendants and the phylogenetic tree that connects them. This can be seen as learning to think as scientists, rather than as learning what scientists have found out.

2. Considered properties that might be shared by all cells. Not surprisingly, many students hadn't yet learned to include Bacteria and Archaea in their thinking about life. I wonder if the students who have taken Biology 112 were the ones who had?

3. Considered how the first cell could have evolved. It's difficult to be very specific, given how little scientists know about this, and difficult to be very thought-provoking, given the little exposure many of the students have had to molecular biology.

What we didn't do:

1. Use the clickers. The PRS software froze up when trying to create a PRS 'lesson' within PowerPoint even though it had worked fine on my computer this morning. To make matters worse, it also worked fine after class, when I tried to demonstrate the problem for the technician from Classroom Services. I suspect it was due to some changed setting on the podium PC that had returned to its default when I rebooted the computer. I'll come in on the weekend and check that Monday's questions are going to work.

2. Spend enough class time on student-thinking problems. I think this will be easy once we're into real genetics, but for next week I'll see if I can come up with a few thought-provoking ones.

Wednesday, January 10, 2007

big pictures

We tackled a number of very big issues in today's class. Probably too many, as none of them got the level of development they deserve.

The clicker questions didn't work. This was my own fault; I had assumed (hoped) that deleting the PRS logo from a slide would delete the associated clicker question, but instead it just created a mismatch between the questions and the slides that sent the PRS software into a tizzy. So we did the science questions by shows of hands, which was fine.

In both classes students raised a point I hadn't anticipated, that phylogenetic trees usually have the deepest branches on the left. I wonder if they learned that in high school. I'm pretty sure this isn't an explicitly-stated convention, but it is commonly done.

Tuesday, January 09, 2007

Learning about and with clickers

We didn't do anything with clickers in the first class, but I want to have some clicker questions in the next one, and to spend a bit of class time on the mechanics. So this requires two kinds of preparation.

First, I need to have a series of steps that get students started with clickers, because close to half said they hadn't used them before. 1. How to program your student number into your clicker. 2. How questioning works. 3. How answering works. For this I need to have a few very easy sample questions, and to allow time that would otherwise be spent on the science.

And there should be have at least one interesting thought-provoking clicker question about the science we're doing. This can come at the end of class, but I should allow at least a few minutes for it.

The pedagogical challenge is to move one or more concepts from lecture-style presentation, in which I tell the students the concept, to question-plus-thinking presentation, in which I raise the question, students evaluate possible answers, then I tell them the answer. The latter takes a lot more time, but gives much more real learning. So this is another pedagogical problem - because I need to spend less time lecturing on other concepts to create time for thinking about the most important ones.

Thursday, January 04, 2007

Why have a 'teaching blog'?

Classes start on Monday, and I've put a link to this blog on the BIOL 121 WebCT homepage (only open to students), so curious students from my classes are likely to start visiting this blog. I doubt that any of their other profs have teaching blogs, so I'd better explain what I'm trying to accomplish here.

This is where I'll be reflecting a bit about my goals for the course. I'll discuss what I'm trying to accomplish in each class and the logic behind the different things I'll ask students to do. I'll probably also consider how to deal with problems (both practical and pedagogical), and now to improve approaches that are not working as well as I'd like.

I'm making it easy for students to read this blog because I'm a big believer in open information. People who study teaching often write about 'meta-learning' (learning about the process of learning) and argue quite convincingly that students who are encouraged to think about how they learn will learn better.

The comments are open (anonymous comments are allowed), and I'll always read them though I probably won't directly respond. Students who want responses should post their questions on the WebCT Discussions Board; I'll create a 'topic' there for posts about this blog, and allow anonymous posting.

And no, the blog material won't be on the exam.

Wednesday, January 03, 2007

Papers for students to report on

One of the Biology 121 project options is writing a report on a peer-reviewed scientific paper. Students are free to choose any paper that interests them, but I'm providing a list of suitable papers as well.

It's nice if the papers are by local researchers, so I've emailed my colleagues asking for suggestions of papers they've written that might be suitable. The paper shouldn't be overwhelmingly technical, which rules out a lot of molecular biology papers, but this course isn't about molecular biology so that's OK. And they shouldn't be too long. And they should be sufficiently well written that students can understand what the research question was and why it's interesting.

When I discussed their papers with last year's students, many said "I had to read my paper five times before I started to understand it!" But they weren't complaining - rather they were proud that they'd eventually mastered such difficult material, and felt that this new skill would be a big help in their future courses.