Assigning Letter Grades to Numerical Scores

This Q&A was adapted with permission from the book Chalk Talk: E-advice from Jonas Chalk, Legendary College Teacher, edited by Donna M. Qualters and Miriam Rosalyn Diamond


Dear Jonas,

I read your answer to “Inquiring Instructor” a couple of weeks ago about how to help our students who are struggling. I also gave my mid-term exam to my first year engineers this past week, and have another problem. The mean score on the exam was a 51, which is lower than I’d like to see, but I feel that I graded it fairly. One of my colleagues said that it’s just that the student quality has gone down over the years. Anyway, students were clearly upset by their scores, even the ones who had done well relative to the mean. All of them were asking to what letter grade (A, B, C, etc.) their numerical scores corresponded. I told them that I really don’t set grade ranges until the end of the quarter and that the exam difficulty would be taken into account then. While they nodded politely I still sensed a high degree of anxiety among the students. What can I do?

Signed: Grappling Grader


Dear Grappling Grader,

In this situation I sometimes wonder if students’ high school preparation is inadequate. As measured by SATs and high school GPAs, the quality of the first-year engineering students has never been better: this year, first-year engineers had an average total SAT score of 1210 (up from 1185 last year), and an average high school GPA of 3.36 (up from 3.20 last year). While their preparation for your specific course may vary, the numbers point to better quality students on average.

With regard to your exam, I would ask myself if the exam was well-designed. I always give exams that I intend to be good and fair, but sometimes, in retrospect, I have to acknowledge misjudgment. While you may have graded them fairly, you might reflect on how it compares to other exams you’ve given. You could do a question-by-question breakdown to see if there are any questions that students, including the best in your class, uniformly botched. This could be the sign of an ambiguously worded or overly difficult question. Was the level of analytical thought required on the exam beyond that required in homework? Was there enough time for the students to both think and work the exam?

The process by which an instructor assigns letter grades to numerical scores is obviously the prerogative of that instructor. But unnecessary anxiety among students, especially freshmen, about where they stand grade-wise in a class, can cut into their motivation to learn. Anxiety can also demoralize them to a point where they might withdraw from a course because they’ve misinterpreted their current grade status, i.e., they think they’re doing poorly when in fact they are doing reasonably well compared to their peers. For example, a student who got a 61 on your mid-term might think this corresponds to a D or D- (from a high school frame of reference). So, should you assign a letter grade to these scores? And if so, how? The answer to the first question, in my opinion, is yes. Remember Jonas’ First Law of First-Year Students: They are in transition, and are still fundamentally high school students and operating from that frame of reference. My experience indicates that first-year students put in more effort and perform better when I clearly communicate how they are doing in my class through the assignment of letter grades after each exam. Throughout high school, letter grades were assigned to numerical scores, and they expect the same at college. Furthermore, in high school, the grade cut-offs were fairly conventional, e.g., 90-100 = A, 80-90 = B, and so on. To go back to the earlier example, if a student got a 61 on your exam, that would be a D- or even an F in high school due to these cut-offs; it probably isn’t that low a grade on your mid-term.

Whatever system you use, it’s important to communicate clearly the letter grades to which student scores correspond. First-year engineers, who are carrying a demanding course load, have many anxieties about their academic performance, and are used to a high school grading scheme, this is essential. Clear communication will motivate them to improve on their performance and keep them from misunderstanding how they’re doing in your class.


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