Posted by: Kenn Hermann | December 8, 2007

Helping Professors (and Students) Figure Out Averages

How difficult can it be to figure out a student’s average? If you do an online search for “calculate grades” you will get a raft of websites that ‘help’ professors and students figure out their grades. You will find many formulas, long detailed explanations, and elaborate spreadsheets, all designed to do the simple task of figuring out a grade. My guess is that if many of my students stumbled across these pages, their eyes would glaze over while trying to follow the complicated math formulas long before they discovered what their average was. Mine sure do.

I remember all of those years ago when I worked with the spiral-bound green (they were always green, weren’t they?) gradebook in which you entered student grades in those teeny, tiny boxes and spent literally hours figuring out final grades by hand based on weighted percentages. If a student wanted to know their average at any point in the semester? Out came the pencil and head-scratching.

I have tried to simply the process for myself and my students. Years ago I discovered the magic of a 1000 point scale — and Excel. Multiplying by 10 eliminates decimal points and weighted grades. I began to assign points for each element of the course grade that reflects its percentage of the final grade. Thus,

  • exam #1, 200 points, 20%
  • exam #2, 200 points, 20%
  • attendance, 150 points, 15% — # of absences = x number of points
  • weekly homework, 150 points, 15% — each assignment = y number of points
  • final exam, 300 points, 30%

Each semester exam is returned with the number of points earned, e.g. 190 points for an ‘A’ exam. It seems easier to tell students that they have earned 190 points than telling them that their 95% is worth 20% of their final grade. One of the bonuses of this scheme is that I now have twice as many points to distribute on the exam than I would for a typical 100 point exam. Likewise, there are 15 homework assignments worth 10 points each (each week is worth 1% of the final grade); it seems easier for students (and me) to understand that they have accumulated 80 points through 9 weeks than to tell them that their 89% average is worth 9% of their final grade.

Students know their current average going into the final by adding up the points earned in each element and dividing by 700 (points earned divided by points possible). They also know exactly how many points they need to earn on the final exam to keep their current grade or boost it. That somehow seems easier to understand than for a student to wonder what percentage she has to score on the final, which is worth 30% of her final grade, to raise her current average of 76% to 80%. That would be easy to figure out. She now has 532 points (76% of 700); that means she would need 268 points (a B+/A-) on the final to earn a total of 800 points, the minimum for a B-.

Students trying to figure out their grades can easily convert their current weighted grades to the 1000 point format. E.g. if an exam is worth 100 points and counts for 25% (.25) of the final grade on a 100 point scale, that means the exam is worth 250 points on a 1000 point scale (100 x 2.5). If the student got an 80 on the exam, it would be worth 200 points on a 1000 point scale (80 x 2.5). See how easy it is?

Of course, creating a simple Excel spreadsheet streamlines the entire process and dramatically cuts the time needed to determine final grades. A few simple formulas, copying them for entire columns, and presto, all done for another semester. It is certainly easier for me to figure students’ final grades by doing the simple addition than figuring weights, e.g.: total points = automatic percentage; 789 points = 78.9% = C+. No fancy formulas, just simple addition does the trick. Long gone are the cumbersome gradebooks, calculators, stubby pencils, and head-scratching. This system is simple, quick, and accurate — and all done without an advanced degree in math.

I am pleased — and surprised — that this blog has, apparently, helped so many people.

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Responses

  1. ah…so that’s why many of my profs go by the 1000 point total scale. Some go a little over, like 1250, or keep all assignments (or group of assignments) on a 100 point scale and weight each assignment/exam group on a 100-point scale, like 30%/30%/25%/10%/5%.

    i think i like this blog. i think i’ll visit it occasionally…at least as long as i’m in college. keep giving us the other side of the story. and i request the occasional, more personal, “stories from the life of a professor” posts.

  2. That would be the reason, Michael. I will try to add some color on how the other third of academia lives. Don’t forget the administrators, who comprise a VERY LARGE third, along with students and faculty.


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