Making the Grade - 1

It is sort of obvious that when a teacher puts 87% on a quiz, a test or a report card that it means something. But what does it mean?

I have no idea.

Of course, I used to do it, but after many years I have come to the conclusion that percentage grading make no sense. There is no acceptable assumption behind using a percentage to indicate how much or how little a student has learned.

A teacher writes a test. The students takes the test. The teacher grades the test and the grade is percentage of the total possible points on the test that the student answered correctly. Sounds very reasonable, efficient and clear.

But it is not reasonable and cannot be. How does the minimum "passing" grade, say 65%, establish that a student who only earns 64% not know enough to pass, while a student with 65% does? How does a score of 65% on one teacher's test compare to a 65% on the test that the teacher in the next room wrote on the same material, or the teacher in the next school district, or the next state?

Then there is the problem of all the students scoring below our expectations. We've all given a test that was too difficult - by which I mean that all the scores were lower than we would like. What to do?

There are lots of things: give a retest, give students the opportunity to earn back some or all of the points they lost by correcting their mistakes, or make sure the next test is so easy that everyone can bring their average up to where it was.

A big favorite is to "scale" the test. Students particularly favor scaling because they get some extra points and don't have to do anything for them.

After teaching a few years teacher can become very good at knowing how to write a test that is not too difficult and the class average will be close to what you (and your principal) would like it to be.

But any and all of these deny the validity of percentage grading in the first place. It doesn't make the grade.

While no system is perfect, the alternative I favor is a type of scaling. In my next post I will discuss some scaling schemes that are commonly used, but also do not have good assumptions behind them. A third post will explain the system I like.

Meanwhile, think about what, if anything, a percent grade really indicates.