I just turned in grades to the registrar yesterday, so grading policies are on my mind right now. One of my policies is that “there is no such thing as extra credit.” I think I adopted this idea from a math and computer teacher in high school. (Hello, Mr. Engler!) But many students and professors love the idea of extra credit, so it's worth exploring why I disagree with it enough to deny its very existence.
There are two perspectives on extra credit, so I'll address each separately. Students generally ask for extra credit opportunities after they have screwed up their initial opportunities. Bombed the midterm? Didn't bother to submit two assignments? Fear not, just ask what you can do for extra credit! Some professors will agree and give you a second chance.
I see a series of problems with this. First, for the sake of fairness, the opportunity must be open to everyone. It's inherently unfair to make special deals with students that seek extra credit, and leave the quiet students out. Now, since the opportunity is open to everyone, that means that everyone must do it, to remain competitive. By assigning extra credit, you are essentially just adding new requirements to the course. There is nothing optional about it.
One way that teachers tally extra credit is to add points to the numerator without adding to the denominator. Arguably, this gives low-ranking students a second chance without hurting high-ranking students; you can't do better than #1. But I think this is wrong. For example, suppose these are the averages of three students after the mid-term exam:
Carol 95%Chris bombed the mid-term, and is in danger of failing the course. So we offer everyone a chance at adding 4 points to their scores. Chris desperately needs that opportunity and moves up to a 64%. Carol is taking 21 credits and doesn't have time for extra work; besides, she's already #1. And so Carlos does the extra assignment and surpasses her; Carol is no longer #1. Maybe in the end it won't make much difference; probably Carol and Carlos will both still earn ‘A’ grades. But the point is that just to maintain your rank (and thus possibly your grade), you must do the extra credit. And so therefore extra credit is not a reward for going above and beyond the regular course requirements, as we like to think. Rather, it is just additional course requirements.
Now, let's look at it from the teacher's perspective. Some teachers love to offer extra credit opportunities, especially for really challenging problems. In this case, marking an exam question as extra credit seems to say, “I don't really expect most of you to get this one, but try it if you want to impress me.” This kind of opportunity is appealing to the top students for the same reason that teachers like it: it helps to separate the good students from the truly amazing ones. I have to admit that this appeals to me too. But calling it “extra credit” seems like little more than a psychological trick, so that ‘B’ students (and below) will not feel demoralized for skipping it. If the question contributes to the denominator, then it's not really optional; and if it doesn't, then it's not fair.
So, if extra credit is either non-existent or unfair, how can we address these different needs? How can we give students a second chance after screwing up, and how can we separate the ‘good’ from the ‘great’ without demoralizing the merely ‘okay’? To give second chances, one could have a very flexible late policy (which I tried but abandoned) or drop the lowest assignment score (which seems to work much better). To separate good from great, I will sometimes include one or two extra-challenging questions, that go beyond the basic expectations. I mark them as difficult, and advise students to address them last. And then I make them worth just a few points. This sends the signal that it's more important to get the basics right, but to get a ‘perfect’ score, you have to go beyond the basics.