In course specification for the course I teach there should be two mid-term exams. For each one that total marks should be 20. I forgot about that and gave the students the first mid-term with only 15 multiple choice (1 mark for each).

Now how can I correct my mistake? Should I give them a bonus of 5 marks or what is the best way to correct my mistake?

It also would be helpful to suggest a book that discuss such situations.

  • 14
    Why not just rescale? I.e., marks/15*20. That might require some rounding, but seems the fairest. Nov 8, 2017 at 12:22
  • 1
    No that is also not the same. If you rescale it, 14/15 would become 18.67/20. Note that these two fractions are equal, which is what you would want, so that someone who got half of the questions right, still gets half of the points. Nov 8, 2017 at 12:39
  • 1
    For example, yes. I don't know the system that you have to use to enter the grades, but in the systems I am familiar with, it is possible to set the weight of the individual tests (i.e. first midterm 20%, second midterm 20%, and so on), and you can set the maximum number of points for each test. In that case there shouldn't be any reason to change the 15-marks bases scores, and the system should calculate the final grade automatically. But again, this depends on the specific of the system you use. Nov 8, 2017 at 12:50
  • 4
    The computer works for you, not the other way around. Announce that you are going to scale the grades, and then make the adjustment yourself (in an offline Excel spreadsheet if you have to) before reporting the final course grades.
    – JeffE
    Nov 8, 2017 at 12:59
  • 7
    A true CS Geek would not need to ask if addition is the same as multiplication. Nov 8, 2017 at 16:08

1 Answer 1



  • Re-scale the grades by multiplying a student's score, x, by 20/15. Thus a score of 12 out of 15 (which is 80%) would become 16 out of 20 (still 80%).

  • Just give them five more questions. Did you plan to get more data for grading purposes? You can always get more.

  • 3
    • Either option works...
      – Solar Mike
      Nov 8, 2017 at 15:04
    • @user138719 how did u know that? have u read a specific resource. I ask because I want to learn.
      – CS Geek
      Nov 23, 2017 at 21:00
    • @CSGeek If you're referring to how to re-scale the grades, I found the student's current grade as a percent (divided their score out of the points possible: 12/15 = 0.8, which is 80%). Then if you meant to have 20 points possible instead of 15, you need to find out what 80% of 20 is, which can be found by multiplication: 0.80 x 20 = 16. I know this because I teach math and I never take the time to "plan" the number of points on an exam -- I just determine the percent earned on a particular assignment and then weight it accordingly in my grade book.
      – user138719
      Nov 24, 2017 at 5:42

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