Grading Explanation

Many students are confused by the numerical grading system, especially when they end up just below the cutoff to get a higher grade. The conversion of leters to numbers allows for three things:

(1) Grades can easily be averaged and calculated with a spreadsheet.

(2) Grades can easily be skewed by formula in a fair way to close the range of the "minus" grades, essentially meaning that more students would end up with a grade of A instead of A- or B instead of B-.

(3) Some grades can be assigned a numerical grade, instead of a letter grade and be counted in the average.

If you think about a logical system that does not include numbers, you would probably come up with something like the following simplistic system. Imgaine a system with two grades: A and B (no other letters and no pluses or minuses) and with no weightings (i.e., all grades count equally toward the final grade). You would expect that if someone got a more As than Bs, that person would receive an A, and if someone got more Bs than As, that person would receive a B. What could be more simple.

All the numerical adjustments and averages simply serve the above purpose with small exceptions:

(1) Some classes have weightings for some grades so a regular paper might count more than a mini-paper, for example.

(2) The cutoff line between A and A- and B and B- in most classes is shifted down so some people who might otherwise get an A-, for example, will end up with an A.

(3) Grades can range from A through F with all + and - grades in between.

(4) Grades can include the grade of A+

Let's take these adjustments one at a time.

(1) This one is easy to explain. In the simple system, instead of counting the number of grades that are A and comparing to the number of grades that are B, simply take the percentage of grade that is A and the percentage of grade that is B. If 50% or more of the grade is A, the final grade is A. If less than 50% of the grade is A, then the grade is B.

(2) In the simple system with A- added into the mix, a student who gets all A and A- grades and gets more A grades than A- grades will get an A, and the person who gets more A- grades than A grades will get an A-. In most of my classes, you will find that the cutoff line is not midway between A and A-. That is, if A is 95 and A- is 92, in the simple system, the cutoff line should be 93.5, midway between A and A-. Generally, I place the cutoff line at just above 92 (sometimes a little higher). This means that if someone gets all A- grades, that person will receive an A-. But if a person gets all A- grades except one A grade, that person will receive an A.

(3) With only As and Bs, numerical equivalents wouldn't be necessary. However, as students earn a variety of grades, the numerical equivalents allow for a way to calculate averages and end up with something reasonable. Someone, for example, who earns one B and several A and A- grades can use the numbers to figure out how much the B will hurt the chances of a final grade of A.

(4) The A+ grade is an oddity and the most difficult to understand. In my grading system, I generally set A to be 95 and A+ to be 100, but A+ grades are rarely achieved. On most assignments, no one will receive an A+. This raises the question, "if I did everything right, why am I getting a 95." The answer is that this is the system, and it works and is fair. If we go back to the simple system with all As and Bs, we can see the logic of this system. If A is given the numerical equivalent of 95 and B is given the numerical equivalent of 85, then the A/B cutoff line would be the midpoint between them: 90. This works! If you complain that you got everything right and still got a 95, then the system could be adjusted quite easily. With A at 100 and B at 85, then the cutoff line would shift from 90 to 92.5, the midpoint between the new A grade and the B grade. So, if you just miss a cutoff and think your A grades should count for 100, feel free to calculate your new grade, but don't forget to adjust the cutoff lines. You are likely to find the new final grade to be the same as the old. The number given to A and B is not really important as long as the cutoff line is always the midpoint.

So, now you ask, what's up with the A+? The A+ allows for two things. First, when grades are given numerically on a 100 point-scale, it is reasonable for someone to get an A without getting a perfect score, and if someone gets a perfect score, that is probably extraordinary. Second, on occasion someone will hand in extraordinary work that goes well beyond the requirements (even well beyond what would be expected for an A). Allowing an A+ in this case acts as extra credit. It is above the highest grade on the scale and could serve to not just balance but make up for a slightly lower grade on another assignment. In the simple system, an equal number of As and Bs would be right at the cutoff line between A and B, but an equal number of A+ grades and Bs would be above the cutoff line. Note that A+ is not an option at Loyola College for a final grade.


This page was prepared by Dr. David M. Marcovitz.

Last Updated: January 16, 2006