Wednesday, 4 May 2016
So I asked the above question on a test today. Plenty of kids got it wrong. In the majority of cases, what mistake did they make? Check out this kid’s work because it’s pretty typical:
He wrongly assumed the first ball wasn’t moving in the start of the problem. He proceeded to solve a conservation of momentum problem correctly in all other aspects. When he hit submit on his test, he saw that his answer was wrong. So he set about finding a correct solution and presented me with this correction:
Yay! Mistake found and solution corrected. (I’d prefer to see a few words along the lines of “originally I thought v1i was zero but clearly it is actually 2 m/s” but this is still pretty great!)
My testing setup:
- Test is given online (this happens to be Moodle).
- Students submit the test at the end and get immediate results. For some questions, I’ve configured feedback for common mistakes (such as “did you notice the sign on this one velocity should be negative?”). Though I can also configure partial credit automatically, I’d rather the kids think about what they did right to earn partial credit.
- Students highlight partial credit or correct anything they can (rubric is below).
Year-to-year feedback from students is that I’m quite generous in granting partial credit. Maybe that’s true but I just feel like you have to know nothing to get no credit on a problem on one of my tests. For instance, identifying all the given values will earn you 25% credit.
BTW, I love this topic and write about it pretty much every time I give a test.