I talked with a senior colleague a couple of weeks ago and he mentioned that grade distributions have become increasingly bimodal. There are kids who have high scores and kids with very low scores, and very few students in between. The colleague said it didn’t use to be like that, that the students 20-30 years ago used to simply be better on average, and grade distributions used to be the beloved normal (Gaussian) distributions.

I don’t know how students used to be, but I can attest that the bimodal distribution is the norm rather than the exception in many of my courses. There are students who are obviously getting the material and who could probably take on even more challenge. And there are the kids who are so far behind and who have so many deficiencies from lower-level courses that it’s unclear what it is that they are actually getting from the class, if anything.

The problem with this profile is that you don’t know whom to aim your lectures at. My best-ever teacher in grad school said “20% of the students will do great no matter how poorly you teach, 20% will do poorly no matter how well you teach, but there are 60% of students where how you teach really affects what they learn and how well they do; you want to tailor your lectures towards the 60%.” The thing I see is that there are 40% who are doing well and 40% who are doing really poorly, and 20% who are doing so-so. The people who are consistently doing really poorly likely shouldn’t even be in this major, but I am not sure what to do about it. On account of them, I can’t do what I could do in class with the students who are doing really well. Rather than a near-continuum of abilities, we have a pretty big chasm, such that most of the class is either really bored or really lost. It seems that there are very few people near the average, for whom the middle-centric teaching approach of my former teacher would work.

What I do is try to assign extra homework with some brain teasers for additional credit, and I already give 2-3 extra problems per exam that require a little non-trivial thinking. But the lectures do still get dragged towards the lowest common denominator, which leaves some kids really bored. I am not sure how to teach to a class with such a wide range of skills. Ideally, the students at the very bottom of the curve would get sent back to take some remedial courses, but I can’t see that being a widely acceptable practice as college costs money and everyone is interested in funneling the students all the way through to a degree, somehow. We as teachers are discouraged from failing students, but then the value of a BS degree of good students drops with every poor students graduating despite having learned squat.

Who is the one who tells a student “Maybe this is not a major for you” or “You need to go back and learn some calculus and then re-take the class”? The thing is that what’s best for the student may not be the best for enrollment numbers on which department budgets hinge. Consequently, we go soft on the people who really should not be getting our degrees. I try to mind my own business and am no rebel, but this issue makes me wish I were. It makes me sick that everything is always only about money, and that even our core mission — educating students — has to deteriorate for this reason.