Calculating a Course Grade

Different grading scales work in slightly different ways, but the typical student's concern regarding grading status usually boil down to "What do I need to get on the Final in order to pass the course, or to get a certain grade overall?" (That was always *my* concern, anyway.)

This page will demonstrate the general methodology of how to answer this question.

The simplest grading scheme is one that involves cumulative points.

How do I calculate my grade, when it's cumulative points?

When the grading scheme boils down to "the entire course is worth [some number of points]" and all points are equal, then, to find out how many points you need on the Final:

1. Add up all the points that you have earned so far (that is, exclusive of the upcoming exam).

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2. Determine how many points, out of the total for the course, are from components of the total grade; that is, find how many points were available for everything before the Final.
3. Divide the number from (2) by the number from (1). This gives you your current numerical grade as a decimal.
4. Convert the decimal to a percentage to find where you stand, at this present time.
5. To figure out how many points you need on the Final to get a certain grade, find the number of the total points available that represent the grade that you're wanting.
6. Subtract the number from (1) from the number from (5). This tells you the number of points you need on the Final for the grade that you've picked.
7. Compare the number from (6) to the points available on the Final. Interpret the results.

Let's see how this works in action.

• A student has earned 76 points (of the 125 points available) on the homework, 102 of 200 points on the Midterm, and 35 of 75 on the lab quizzes. The grading scale is as follows: A: 540 points, B: 480 points, C; 420 points, D 360 points. The Final is worth 200 points. He isn't worried about his grades so far, because he figures he can "pull it out" on the Final. (a) What is his current grade in the class? (b) What is the highest course grade the student can get? (c) What grade is he likely to get?

This example shows why it's important to invest a lot of effort early on in the course, while your mind is still fresh. In all my years of teaching, I've never yet seen a student "pull it out" on the Final, but I've seen many flunk trying. Don't wait until the end; learn the material up front and on time. Start asking for help as soon as you find yourself in difficulty.

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A point-based grading scheme might have the course grade given in terms of percentages, but the computations will mostly be the same.

• A student has earned 112 points (of 125 points available) on the homework, 196 of 200 on the Midterm, and 68 of 75 on the lab quizzes. The course grade is out of 600 points, with the Final being worth 200 points. She wants an A, and the grading scale is as follows: A: 91%, B: 82%, C: 73%, D: 64%.
  (a) What is her current grade in the class?
  (b) Can she get an A in the course?
  (c) If so, what does she need to get on the Final? If not, what is the highest grade she could get?

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• In a class worth 1,000 points in total, Bryce has earned 182 points (of 200 possible) on his homework, 124 points (of 200) on his essay, 79 points (of 100) on his quizzes, and 69, 72, and 81 points (of 100 points each) on the tests. He would like to get a B in the class.
  (a) What is his current grade in the class?
  (b) Can he get a B in the course?
  (c) What grade would you expect him to get for the course? (Include your reasoning.)

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The grading schemes above are pretty easy to compute. To find out how you're doing in any grade component's subscore (for homework, for instance, or for the quizzes), you just divide the points you've earned by the points that have so far been available to be awarded in order to get your percentage on that subscore.

To find out what you need on the Final, you add up the points you've earned so far in each grade component. You subtract this from the number of points necessary for the grade you're wanting to get overall. Then divide the result by the number of points on the Final, to get the percentage grade you need on the Final.

And you can evaluate how reasonable that Final percentage grade is by comparing it with your subscore percentages.