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Student views on grading

September 23, 2012

In class, we make extensive use of PET-style energy diagrams. A source/receiver energy diagram includes energy changes in each object, energy transfers between those objects, and a label for each type of interaction occurring. Here’s an example of a ‘complete’ energy diagram for a hand pushing a cart on a low-friction track:

I wanted students to think about different possible errors that a student could make when sketching one of these diagrams and to think about what should be considered ‘big errors’ and what should be considered ‘small errors’. To guide this discussion, I made a handout containing three energy diagrams for a person catching a ball. Each diagram contained one error:

  • Diagram A – the energy transfer was labeled as kinetic energy
  • Diagram B – the interaction label was missing
  • Diagram C – the energy change in the receiver was missing

The handout asked students to discuss in their groups and decide which diagram should receive the most points and which diagram should receive the fewest points. This discussion went very differently than what I was imagining when I planned this activity.

The majority of students (most of whom are elem. ed majors) started arguing for points based on everything except understanding. Lots of comments like ‘maybe the student ran out of time’ or ‘at least the student tried in A, in B and C she didn’t even try.’ Once I proposed that we all assume that the diagrams represent everything the student knows, the discussion aligned a little more with evaluating understanding.

Some students felt that labeling the transfer as kinetic energy was really bad because differentiating kinetic energy and mechanical energy was something we discussed in the very first activity. I reminded students that this is our own distinction that we made as a class and that when they become teachers their own curriculum might not use the term mechanical energy in the same way we use it.

Several students felt like labeling the interaction was not that important but they had difficulty articulating why they felt this way.

Multiple students talked about wanting to see the narratives that would accompany the energy diagrams. They argued that from the narrative you would be able to tell if the student really understood the ideas. I’m happy some students took this perspective as I’ve been promoting the energy diagrams as a tool to help us construct verbal descriptions of what’s going on and not as an ends in themselves. It would have been interesting if I had connected this idea to the use of discussions in our class (within a group, between a group an myself or an LA, whole class discussions, etc.) but I didn’t think of this in the moment.

Some students built on the ‘at least she tried’ idea and argued that having an answer was better than having no answer but that the answer did need to be reasonable to count. I wish I had had the time to pursue this further and flesh out what ‘reasonable’ means and what criteria we might use to differentiate reasonable and unreasonable answers.

In the end, the students voted on how we should rank the diagrams and I said I would use their consensus when grading energy diagrams on the quiz. Neither of my classes ended up ranking the diagrams the way I would have but I decided not to push them in my direction. Instead, I said that we would return this question later in the semester and see if our ideas have changed or if we still like the current ranking.

Overall, I think this has the potential to be a valuable exercise. There were some more productive and less productive discussions. In the future, I might set the activity up as discussing ‘what does each student understand or not understand’ and then connect this to the question about grading at the end rather than asking about grading from the start. Even with its flaws the activity gave me some unexpected insight into how students are thinking about grading and (I think) also contributed to the sense of ownership the students feel in the classroom.

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