Some years ago I taught an on-line college course that I had never taught before, and I wasn’t given much guidance about grading at all. I took the approach that I was concerned with mastery, not with grade distribution, and I created a rubric that told the students what I intended to require in order to obtain various grades. I think it worked pretty well. I will say, though, that the first couple of times I taught it, I had to look closely at how the students were doing on the tests to determine if the tests were “too hard” or not. I’ll also note that the students pretty much sorted themselves.