What grades should look like

Another riff emerging from a conversation at SICB...

My students may not like knowing this little fact about my teaching philosophy. I tend to think a grade distribution should look like this.



C, being the middle letter grade, should be average. An A should be fairly unusual... but so should an F. Now, I'm not saying my grade distributions actually look like this. They're often skewed one way or another. And I'm okay with that. Every class is different, and I don't feel there's any reason to have any particular distribution of grades. And, interestingly in the context of this discussion, nobody in my institution has really said I should have any particular sort of grade distribution. I do submit my grade distributions during my annual review.

I had a very interesting conversation with a colleague at a different kind of higher educational institution. Her institution expects grade distribution like this:



I'm not sure of the distribution of Bs and Cs, but I distinctly remember 25% As, and 5% Ds and Fs combined.

And if the grades deviated from that too much, a faculty member could conceivably get in trouble.

I'm tired right now, so don't want to comment about the pros and cons of either scheme. But I had never really encountered someone working under such a significantly different regime.

Being an empiricist, I wonder if there's any evidence of what grading system produces the best outcomes.