Occasionally I hear from other physics teachers that they have been asked to adhere to a school-wide, non-negotiable "grading scale." They mean that some administrator has decided by fiat that 90% is an A, 80% is a B, with no flexibility.
Of course that's ridiculous. Each teacher grades with her or his own idiosyncrasies. As long as grading standards are clear, translucent, and applied across the board, no one should worry. In fact, I have it on good authority from multiple college counselors that university admissions people are well aware that different schools, different departments, different courses, and even different teachers assign grades to somewhat different standards. Admissions officers ain't stupid; they won't be pleased or tricked by an artificial standardization attempt.
But everyone has colleagues somewhere who advocate a form of grading in which "90%" has some sort of intrinsic meaning. If you require 85% for an A, and your colleague in the history department requires 93% for an A, aren't his students at a disadvantage? Well, no. A family who makes 5 million yen is not more than a hundred times times better off than someone making 40,000 dollars...
Today I heard a number of conversations in which folks were advocating for a standardized school grading scale. Here's my response.
Physics multiple choice questions do not ask for recall, or even for application of an algorithm. They ask for application of facts and equations to new situations. Similarly, free response items ask students to engage in creative problem solving in new situations. We don't ask "In lab last week, how fast did the cart move?" We ask, "You're asked to predict and then measure the speed of a cart on a bumpy track that you've never seen before but I'm just now describing. Go." Students are not expected to get 90% of the available points, any more than a soccer player is supposed to score on 90% of his shots.
On the AP exams, 65-70% is a 5, which the College Board has carefully correlated to an A in the best college classes. On the New York Regents exam -- on which our conceptual program is based -- 85% is roughly equivalent to an A. So we use these well-known and well-verified scales in physics.
I'll never understand why people get so worked up about grading scales. In English or History class, we can certainly call 90% an A, 80% a B. But really, when you're grading an essay, what does an "89" mean, anyway? And don't people manipulate grades through "bonus" questions, "extra credit", controlling the difficulty of questions, and controlling the grading rubric?
Our all-world quarterback's completion percentage was only about 75% this year... so he's a C quarterback, and the division 1 powerhouse football schools recruiting him should cut him loose. And even our star baseball player in 2010 only hit 0.570 his senior year; he's an NC. I don't know what these colleges and minor league teams were thinking, recruiting him. His batting average is a failure.
Oh, think I'm being silly? That's the same argument as "we must use the same grading scale in physics as in English or Spanish."
If the school demands that we adhere to a strict 90/80/70 scale, I will obediently give Ds and NCs to everyone in my honors physics class except one person, who will have a B. We'll still have straight 4s on the AP Physics 1 exam, of course, but I suppose that's irrelevant.
(P.S. Funny thing is, even though I've heard some very loud voices in favor of a standardized grading scale, it seems that a great majority of faculty, even those outside the science department, in fact agree with me. Most people I talk to quietly don't understand why there might even be a discussion.)