1. The next time a student asks you to grade on a curve, ask him/her why it's called a "curve." In my experience, the ones who ask for a curve don't know what it is they're really asking for. (In their minds, they're asking: "will you give me extra points that I really didn't earn, but would be happy to have anyhow?")

2. As you pointed out, centering the distribution around "C" would fail half of the class. If we take "C" to mean "passing," then the days of "C" meaning "average" are gone. (That is, unless we simply declare 3/4 of all students to be "above average!" :-)

3. I have a less scientific method for assigning letter grades. No "curving" here. Instead, I list the point totals in order, and look for "clusters" and "gaps" -- the idea being, if several students have very similar point totals, their overall letter grades ought to be the same. If there's a large gap between two such "clusters" of students, then that indicates a good place to put a letter grade cutoff (if it's reasonably close to one of the traditional 90%/80%/70%/60% benchmarks).

Granted, this method is somewhat subjective. However, until someone shows me a truly objective grading system that really works, then I'm comfortable with using my judgment, at least to this extent...

Comments?