In a recent post, Parrhesia suggested that course grades should be 100% determined by performance on a final exam—an exam that could be taken repeatedly, with the last attempt being the course grade. (See also the discussion at r/slatestarcodex.) The idea is that grades are supposed to measure what you know, and if you do well on a final, then you know the material.

Ha. Haha. Hahahahahahahaha.

Now, I sympathize with this proposal. I largely agree with the central claim that this would be more accurate than grades based on a mixture of homework and quizzes and whatever.

And yet—I suspect this proposal hasn’t seen much contact with people who’ve actually taught classes. Systems with humans in them behave in funny ways, which means there are other considerations beyond accuracy.

I don’t mean to suggest that things are optimal the way they are. But we should at least understand how they came to be, so let’s follow Chesteron’s fence for a while, shall we?

Here are some things that I hated as a student. At the time, I thought my teachers didn’t understand or care how terrible they were. I now see them as the result of structural forces.

Assignments with agonizingly precise instructions

As a student, I often got assignments that a sane person would write as:

Assignment:

1. Build a temperature monitor circuit.
2. Test it to prove it works.
3. Write a report.

But they wouldn’t be written like that. They would be written like this:

Assignment:

• Step 1: Get a 400-point breadboard. (YOU MAY NOT USE AN ALTERNATE BREADBOARD. NO EXCEPTIONS.)
• Step 2: Write by hand the statement “I have used a 400-point breadboard. In particular, I have not used a 630-point or 830-point breadboard and understand that all credit on this assignment is forfeit if I did.” Sign and date below. (MANDATORY: ASSIGNMENT WILL RECEIVE NO CREDIT IF SKIPPED.)
• Step 3: Place the breadboard on a table with the long axis facing at an angle of 22 degrees from magnetic north.
• Step 4: Take a picture of the breadboard next to a compass and your student ID. (MANDATORY: ASSIGNMENT WILL NOT BE GRADED IF PICTURE IS NOT INCLUDED.)

…

• Step 134: Format your measurements in a 13 x 9 table. Each entry must be written with 4 points of precision. Format this table in 12-point Palatino font with a font-weight of 500. (MANDATORY: AN ALTERNATE SERIF FONT WILL HAVE A 10 POINT PENALTY AND THE ASSIGNMENT WILL BE RETURNED UNGRADED IF A SANS-SERIF FONT IS USED.)

Why? Why so much pain?

Here’s how this happens. A sweet optimistic teacher begins their career. Remembering their own agony, they give out the nice version of the assignment. And when students submit their solutions, most are fine. But some are an assault on reason, with every word of the assignment creatively misinterpreted. It was never stated which temperature circuit to build or how to prove it works or what level of explanation was necessary. And who’s to say what “build” means?

The teacher protests that students should be “reasonable”. And most of the students are amazingly gracious and drop the issue. But some don’t, and they keep complaining and asking for regrades, and if those aren’t accepted they (or their parents) contact the principal/chair/dean/ombudsperson, who are required to have an investigation.

The teacher never seriously worries they’ll get into trouble—often the investigation is a sham—and in the end they’re vindicated. But the whole thing was a huge headache and very much not what the teacher accepted an Xtra-Lite salary to spend their life doing. So, next semester they add a bunch of clarifications. But nature finds a way: That gets misinterpreted