On using old exams

I have always been a strong proponent of student empowerment. I fought to get students onto important administrative committees, such as the ones deciding tenure and promotion cases of faculty members. I have for some time been pushing for a Web-based summary of written comments on instructors, run by students in a responsible and disciplined fashion, as is done at some top US schools. For years, I sent extra paper copies of exams to the Mathsoc Exam Bank (a service run by the student society), and e-mailed in electronic versions for the associated Web page.

I still believe in student empowerment, but I have stopped cooperating with the exam bank, because I think that its few positive aspects outweigh its potential abuses. There is a difference between empowerment and endangerment.

Here is how I think the exam bank can be used correctly: as source material for a simulated exam. If a student prints out an exam but does not look at it except to find out the original duration, sets aside that block of time, and sits down and writes the exam for practice, that is a correct use. It can be quite valuable, as it is a more active form of studying than rereading one's notes.

I don't know how often this occurs, but evidence suggests it is rare. Whenever students come to me with old exams to ask about specific questions, they never have written-out answers. When I ask them to go away and try to write out an answer, I rarely see them again. The same thing happens when someone posts an old question to the course newsgroup, and I reply with, "That question is from the Fall 2002 exam. What have you come up with so far on it?" This is usually followed by silence. One undergraduate tutor with whom I've worked always announces that he will correct any worked-out exam questions students give him. He says it's an easy promise to make, as no one ever takes him up on it.

There are two incorrect uses of exam banks that I often see. One is to use exams as a guide to what future exams will be like. Courses vary considerably from offering to offering. In computer science, we often revise courses and change textbooks. One instructor may decide to use different settings or notation to teach the same concepts. I usually have students coming to me in a panic because they cannot do questions on old exams, and I have to tell them, "We didn't cover that," or "What we call X, this instructor called Y."

After writing an exam of mine, I have had students complain that it was, say, "not like the Fall 2002 exam." My answer is usually something like, "The Fall 2002 offering was taught by a sessional hired for one term who didn't bother to look at past practice and set an exam more suited for a night-school course." But even if it had been set by a regular faculty member, it might have been someone new to the course, or someone who inappropriately ignored the handbook description and put more emphasis on their favourite topics. Why should an exam I create match the easiest or most unbalanced exam in an exam bank? Some instructors may make up exams that are too hard, but students are usually able to identify and discount these. However, they don't seem to discount the exams that are too easy.

The other incorrect use of the exambank is as a source of examples for "pattern matching". Pattern matching is a technique for trying for part marks by recognizing the general form of a question, writing down an example learned in class, and tweaking it in the hopes of coming close to the right answer. It doesn't demonstrate any real understanding of the concepts. Some students seem to confuse pattern matching for genuine learning, or have cynically decided that this is a way to earn credits. I have noticed solutions to old exam questions, or from assignments earlier in the term, appearing on exams I am marking. My questions are different from the earlier ones (I can read old exams, too) but sometimes the solutions I get are not changed at all. This is more frequent when we allow a one-page "crib sheet", which is supposed to spare students from memorizing facts instead of learning ideas. Instead, it encourages some students to copy out solutions to past exam questions without even committing them to memory. I instruct my markers to watch for pattern matching and not reward it. "Crib sheets" are another empowering device I am reluctantly abandoning.

I originally titled this article "Mathsoc Exam Bank Considered Harmful", inspired by a famous paper by Edsgar Dijkstra called "Gotos Considered Harmful", which referred to the goto statements found in many programming languages. Goto statements are occasionally useful, but they are far too easy to abuse. In recent years we have stopped lecturing about them, even their beneficial uses. I know that the Mathsoc Exam Bank is not about to disappear, and even though I have stopped submitting materials, my exams will probably find their way onto it anyway. My hope in writing this is that some students will think about how their uses of the exam bank might be doing them more harm than good.

(Adapted from an article published in the student paper mathNEWS on October 22, 2004.)