By Kevin Cheung, Associate Professor, School of Mathematics and Statistics
About 10 years ago during a lunch conversation that drifted into a discussion on student grades, a colleague asked, “What is an A+?”
The question was of course rhetorical. My colleague simply used it to point out the deficiency of the letter-grade system when it comes to distinguishing top students. I was used to a numeric-grade system as a student. When I first joined Carleton, I did find it surprising that only letter grades appeared in the transcripts for courses in STEM disciplines.
At Carleton, as well as at many other universities, A+ covers a 10-point range, whereas B+, C+, or D+ covers at most half that range. From my experience, there is often a notable difference between students at the top of the A+ range and those at the bottom. However, it is difficult to say the same for students in the D+ range, for example.
For the A+ grade to make sense, it must be a grade that is incredibly difficult to obtain. Otherwise, collapsing a 10-point range into one single grade could make judging a student’s academic ability from the transcript difficult. A piece in The Charlatan some years ago also described the impact of Carleton’s letter-grade system.
One might argue that students in the A+ range are all academic high-achievers and so there is little need to differentiate between them. Such an argument, unfortunately, does not seem to be supported by evidence. Studies have shown that there is a difference in performance between employees with high ability and those with very high ability. A massive longitudinal study on mathematically precocious youth showed that intelligence test scores within the top one per cent were still strong predictors of later creative accomplishments.
A mark of 100 is very far from a mark of 90. A letter-grade system that reflects this reality would be quite desirable.