Day 169: Partial Credit

Friday, 9 May 2014

Student work I’d rather not see next year.

I’ve written before about my system for partial credit but one paper from today’s quiz has me thinking again how I can improve this system I already like. The system rests on the confidence I have that students can explain a correct solution given the answer to the problem.

Above is a kid who struggles to earn partial credit through an approved method: either correctly identifying his mistakes or by showing a (new) correct solution. Instead, he always tags his mistakes as “math” errors with no indication of what exactly the error was, which is totally unhelpful to him or me.

Oh, and for the curious, here’s the question he was attempting to solve:

Screen Shot 2014-05-13 at 7.42.34 AM

My goal is to have kids do one of the following when correcting tests:

  • spot and circle a silly mistake such as a dropped negative sign, a misplaced decimal point, or a small algebra error — which results in automatic 3/4 credit for the problem;
  • fix a physics mistake such as assuming an incorrect initial velocity or misapplying the Conservation of Momentum — which results in between 1/4 and 3/4 credit for the problem; or
  • realize they totally screwed up a problem and (given the answer) show a full & complete solution alongside their original (wrong) work — which results in 1/4 credit for the problem, assuming nothing they wrote before was correct.

While the above list focuses on kids correcting work after they’ve submitted the test, they can also earn partial credit for showing work initially that’s correct. For example, the kid who identifies all the variables in the problem gets 1/4 credit, the kid who chooses the appropriate equation to apply gets 1/4 credit, and the kid who draws an appropriate sketch gets 1/4 credit.


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