A recent discussion with a friend reminded me of an idea I had in high school: in order to encourage students to focus on course subject and content rather than difficulty and to reduce the variability in the grading system based on instructor, the current letter grading system should be replaced with Z scores: (numeric score or GPA – mean) / standard deviation, where the mean and std. dev. are grouped by course and professor (but cumulative over semester). Consequently, lower scores in more difficult courses would be competitive with higher scores in less difficult ones. Additionally, as I’ve seen twice, there are professors (and they were algorithmists both times) who simply do not give out “A” grades. Thus, under the current system, achieving a perfect GPA is as much a matter of avoiding these professors’ courses as it is a matter of performance. Under a system that takes the mean grade of the professor into account, however, they could not harm students GPAs in this way, as their means would be lower than other professors’.