Wednesday, May 26, 2010

Granularity of Grading Scales

One thing that has always bothered me is the granularity of grading scales. The point of the exercise of giving a grade should be an attempt to classify how well the student learned the material. It seems reasonable to classify this level of understanding into “not at all”, “not very much”, “ok”, “pretty well”, and “excellent”, which seem to correspond to the typical F,D,C,B,A. What does NOT make sense is to assign a number on a scale of 0-100. A grade of 67 seems to indicate somehow that 67 percent of the material was learned. This is, however, not at all the case. Rather, it means that the student answered 67% of the particular questions posed on this assignment correctly. It is extremely rare for faculty to ask exactly the right set of questions to determine if every concept was learned in a reasonable way, so this number seems just about meaningless. I have always been in favor of oral exams. I find it extremely easy to, within a 5 minute conversation with a student, classify their understanding of what they should have learned into one of the five categories described above. I guess at some level you’d have to buy into my “Teach the Why not the How” concept (http://daviddoria.blogspot.com/2010/05/teach-why-not-how.html) to realize that it doesn’t really matter if a student is able to produce the correct numerical value on an exam question, but it is EXTREMELY CRUCIAL that they understand the general “what is going on”. I understand that in large classes they are not reasonable, and this would certainly need to be addressed in order to implement such a system on a large scale.

1 comment:

  1. Something I learned in a class at college goes along well with this post. If a concept is missed in a typical class, there is no real chance for the student to go back and learn it without falling behind. I had an engineering finance class that was pass/fail and each assignment was graded similarly. If you understood what was going on and got the right answers, you passed. If you didn't, you had to redo the assignment (with some hints from the professor) until you got it right. Some people learn well the first time through and others need to iterate. The current system caters to the first group and leaves the other group struggling to keep up. I tend to need multiple exposures to complicated concepts before I really understand, so I belong to the second group. This is parallel in my opinion to the granularity of the grading scale not effectively teaching the material or assessing what was learned.

    Also, it makes absolutely no sense to assign a completely meaningless (let me explain why) numerical value (GPA) to someone on their transcript that somehow is a gauge for others to differentiate their level of intelligence from another applicant. Say I earn a 90% on a test and you earn 88%. The curve is 1 point, so you receive a B and I receive an A. This absolutely does not effectively differentiate the amount of knowledge and conceptual understanding of what was being tested. However, it will greatly impact our respective GPAs. It's possible that I simply understood how to solve the problems better but you understood the concepts much more thoroughly, but an employer comparing our transcripts would think otherwise based on the numbers. Yes, the interview process is supposed to weed out people who don't really understand, but the person who truly did grasp the material and concepts may have been weeded out by a machine and denied the right to an interview because of their GPA.

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