Some Thoughts on Peer Grading

Suppose we listened to two pianists play the same sonata. Suppose one of them is a student who has been playing for a couple of years and the other is professional concert pianist. Or suppose we look at two drawings of the same hand, one by a high-school student of ordinary ability, the other by a professional illustrator. I’m going to presume we would quickly agree about which is the better performance. What I want to emphasize is that I can make this presumption without assuming anything about your abilities or claiming anything about mine. We can be less competent than all four of these “artists” and still judge them. We can say something about “how good” they are at playing the piano and drawing hands without being any particular good at it ourselves.

In the cases I’m imagining, our judgment–of relative competence–will often be quite accurate. Obviously, we’ll get into difficulties if we’re given twenty-five professional pianists to rank in order of mastery, but I don’t think we’d be as hard pressed if we’re given, say, a randomly selected group of twenty-five 18-year-old college students. Put them in front of a piano and ask them to play Bach, or give them a piece of paper and pencil and tell them to draw a hand, and we can pretty quickly sort them according to their relative skill at these things. In fact, if we’re asked to assign 3 As, 6 Bs, 8 Cs, 6 Ds, and 2 Fs, we could probably do it. That’s a rather marvelous fact to think about.

Now, if the students weren’t randomly selected but, instead, were taking a piano class or a drawing class, we’d want to have the competence of a teacher to confidently distribute grades like that. But what about the competence of the students? Could students in such a class distribute grades on the curve I’ve proposed? I believe they could, with a certain degree of accuracy, and I believe that the effort of doing so would be instructive–it would teach them something. Indeed, I believe that the ability to accurately discern the relative skill of two pianists or two artists (and therefore accurately predict the outcome of a competition between them) is itself a valuable skill that comes with mastering the relevant art. That is, as I suggested in my last post, it is in principle possible to grade students on their ability to grade each other. Developing their own eye for competence in the disciplines we teach should be part of the learning goals of any course. Even students who would give themselves failing grades in a course can make a qualified guess at what grades their fellow students will get by reading their essays. Just the effort to make that guess in 25 concrete instances will teach them something.

Let me say one last thing. I think it would be good for students to grade a class set of peer essays every once in while, even if just to develop an appreciation for the task that faces their teachers as a matter of course. Students often don’t take the problem of judging the competence of others seriously enough. By giving them this task, and by putting something at stake (i.e., grading them according to how well they predict the teacher’s grades), they will learn to value good, clear writing that is easily judged. After all, the purpose of academic writing is not impress the reader with your intelligence but to open your thinking to criticism from your peers. I think this idea needs to be tried.

I’m happy to hear from people who have.

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