Risks and Rewards of Partial Credit

photo credit: Flickr user "tehbeiber" - used under Creative Commons

photo credit: Flickr user “tehbieber” – used under Creative Commons

Let me tell you what’s been on my mind lately. Partial credit. By partial credit, I mean assigning a point value to a student response that is less than the highest possible point value for that problem because the student didn’t get the final answer correct, but the solution process wasn’t completely incorrect. I have traditionally used this as a grading technique for for multi-step tasks.

In some ways it seems natural. You are giving a student points for evidence of learning. If a student is attempting a 3-point task, fumbles up on one single step and so ends with a wrong answer, shouldn’t the student get to salvage a bit of “credit” for performing portions of the problem correct?

In some other ways, though, it would seem natural that if a student gets incorrect final answers for most or all of the problems on a math assignment, the score wouldn’t be very good. However, through the use of partial credit grading, it is possible for a student to earning a decent grade on an assignment having not actually gotten any of the questions correct.

This problem has blown up on the last unit test for my Algebra II students. This is a class where I am one of three people involved in teaching and planning and I have been out-voted to create exclusively multiple-choice tests, which, becomes a serious problem if students aren’t getting final answers correct. The grades that went into the book were stress-inducing for many of my students.

So, therein lies my conflict. I hope that blogosphere will be willing to chime in to help me.

It could be that I’m too liberal with my use of partial credit. (It has occurred to me to award no more than half-points to a student response that has an incorrect final answer, not sure how I feel about it.)

It could also be that I’m worrying for nothing. (It has occurred to me that if a student can earn 80% of the points on an assignment, perhaps they, in fact, know 80% of the math and so it is an appropriate grade. The 20% they are lacking simply consists of parts that mess up the final answer.)

It could be that this is a problem only because of the difference in assessment styles. I am not a big multiple-choice fan and so I often give constructed response questions.

A quick editorial statement: This all seems to be an issue because our system seems addicted to assigning grades to everything. My favorite solution to this problem would be to eliminate the assigning of point values and grades, but that seems like a long shot at this point…

Thanks for your help everyone.

3 thoughts on “Risks and Rewards of Partial Credit

  1. You are spot on, unfortunately most classes are moving toward mc tests. It is easier on the teacher to grade and it is easier on the district to track the growth ( I use that term loosely) with mc. So if a student forgets to put a negative sign in their formula somewhere and comes up with the wrong answer, that means that they don’t know anything about the formula and shouldn’t earn any points? I suffered through that grading mentality in school and was often frustrated with it.

  2. I really like the idea that you are questioning how we evaluate students. I was a terrible math student and often got wrong answers even though I understood the process. I realize now part of the reason was an undiagnosed visual problem. In spite of that fact, it’s hard for me to accept partial credit in math for a wrong answer. I don’t have the answer for your dilemma but am glad you are working on new ideas.

  3. I also struggle with this concept. As a graded I’ve found that I am less generous with my partial credit when there is a striahgtforward way to check the answers. single varriable equations thats you can substitute in are one example where I give less partial credit. Another is graphing lines, All of the points are solutions to an equation so they can plug in a couple to check their work. One problem I’ve run into with this is that an arithmetic error may go unnoticed by students who are checking their work. if they got 6/2 is 4 when solving, they may make the same error 4 x 2 = 6 when checking.

    Soemtimes I think that if we didn;t give partial credit, students would show more care in their work to be accurate, but I agree that “answers” aren’t the best indicator of learning.

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