So here's a puzzle about the psychology of grading. Harvard and Stanford Law schools have recently announced moving from a letter grade system with pluses and minuses to a High/Pass/Low-Pass/Fail system. My sense is that most students like the change: Students perceive that it takes pressure off them.

  But imagine a slight change. Imagine that instead of adopting the High/Pass/Low-Pass/Fail system, the schools kept the letter system and simply dropped pluses and minuses and the "D" grade. In other words, the possible grades became just A, B, C, and F.

  My sense is that students would object strongly to such a system. They would object that it was too arbitrary and unfair, because a student who earned a very high B or a very high A would get no credit for it: They would just get the flat grade that didn't reflect their achievement. Indeed, I suspect some students would say that removing pluses and minuses would increase the pressure on students by giving students a single bar to hit rather than more of a sliding scale.

  Why is this a puzzle? Well, the two systems are the same in a functional sense. High is just a new name for an A, Pass is the new name for a B, and Low Pass is the new name for a C. But my sense is that students don't see it that way. My best sense of why is that the experience of having received letter grades for almost 20 years of schooling before law school gives those letters tremendous meaning that new words like "high" and "pass" don't have. A switch to a new grading system makes the new grades feel different, even if the switch is mostly just a label.