Some of the work I grade does not seem to be copied verbatim, but also seems close enough that one student or another is being a parrot and does not totally understood what they are saying. My students are working under a collaboration policy similar to the example on this page, which says "Peer collaboration is highly encouraged. It is a highly efficient and fun way to learn [statistics]. However, your homework must be entirely your own work and in your own words." If Alice and Bob discuss problem 3, shouldn't I expect Alice's words, mathematical notation, and problem-solving strategies to appear in Bob's writeup? Please advise me on how to reconcile "collaboration is great etc." with "homework must be entirely your own work."

I have browsed all the other questions tagged grading and a few besides; none seemed relevant.

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    Was the collaboration policy set by someone else, i.e., are you a TA dealing with the professor's policy? BTW, from what I've seen of the published evidence, collaboration appears empirically to be a negative thing for learning. There is some discussion of this in Academically Adrift: Limited Learning on College Campuses, Arum and Roksa, 2011, at p. 100. They cite research showing that "social learning" is negatively correlated with improvements in critical thinking.
    – user1482
    Commented Feb 12, 2016 at 4:50
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    Yes, the policy was set by my supervisor, who is running the course. Thank you for the citation. Commented Feb 12, 2016 at 17:31

4 Answers 4


That is why I have a rule that for each homework a group of students is selected "at random", and asked by the TA to explain what they turned in. The grade of the interrogation replaces the homework grade.

Rationale is that I really don't care (too much) if they copied from the Internet, got it in an obscure book somewhere, or worked it out in a group. I want them to understand, and this forces them to at least be somewhat familiar with the solution they hand in.

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    We ran this policy in even a very large course (500+ students) with a great deal of success. It requires a pretty significant investment, but it both helps catch plagiarism and gives you a good idea of how well everything is being understood.
    – sapi
    Commented Feb 12, 2016 at 7:08
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    Excellent idea. Will do this from now on.
    – JoErNanO
    Commented Feb 12, 2016 at 10:05
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    I would be concerned about fair assessment. I am suspicious of bias from knowing a student's identity, and it really helps me grade consistently when I have written submissions: I like to backtrack, rethink, and revise. Maybe I could revise your method in a way that works for me: perhaps a short written in-class quiz rather than an "interrogation?" Commented Feb 12, 2016 at 17:54
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    @eric_kernfeld, a face-to-face confrontation allows to probe deeper than a quiz. There are often different ways to solve a problem, so asking about the specific solution turned in is exactly the point. Besides, just a handful is selected each time and there are enough homeworks to get each a fair chance at having to explain their work, so the end result of any bias is limited.
    – vonbrand
    Commented Feb 12, 2016 at 17:59
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    -1 Despite being accepted, this doesn't answer the question at all. The TA is not in a position to set a policy such as this so the advice is irrelevant. They asked for advice on where to draw the line between collaboration and plagiarism and this answer doesn't address that even slightly. Commented Feb 12, 2016 at 18:11

This is one of the reasons that for certain assignments I have been moving slowly away from grading homework individually to grading on completion and posting solutions and/or having students discuss answers in groups in class (that will be different from the ones they may have worked on the homework with). As vonbrand notes, the idea isn't so much for them to get the solution, but to understand the solution. If they just copy it without understanding, they may get some credit on the homework, but they'll bomb other forms of assessment that are more heavily weighted.

But if you really want to encourage collaboration while making it clear that work needs to be done individually you could specifically design the assignments around that idea. Each assignment could have collaboration-friendly questions and individual-oriented ones. The instructions could then say something to the effect of "You may / are encouraged to work with a partner on questions 1-3. Then do questions 4 and 5 on your own. If you check your work with your partner afterwards, please make corrections in a different color ink". This would codify the final two steps of the me, we, y'all, you progression in the one assignment and would still allow for them to check their work before handing it in and help them visualize missteps so they can avoid them down the road.

  • "If they just copy it without understanding, they may get some credit on the homework, but they'll bomb other forms of assessment that are more heavily weighted." We do observe this phenomenon in my class. Commented Feb 12, 2016 at 17:57
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    +1 for ideas to separate individual work and collaboration and make visible the different results. Commented Feb 12, 2016 at 17:59
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    I think one of the problems is in a real collaborative setting, each participant already knows what they're doing in their respective role. If you assign a building-block problem that a student has to work out to learn the concepts and principles that underlie everything, you run into a problem. I don't think collaborative assignments are the place to learn the material. I think they need to be the place they can exercise application and critical thinking. Some thoughtful assignment design is then critical here. At least then they can work the fundamentals to exhaustion if they cant answer.
    – CKM
    Commented Feb 12, 2016 at 20:11

It really depends on the nature of the work and the established guidelines for grading that type of work. If it's a class of physicists in graduate school who are expected to find solutions to complex problems and collaboration is expected in determining the missing pieces to the puzzle, then there really can't be any serious expectation of wildly different proofs. If their collaboration failed on a problem because everyone counted on one member's interpretation, then it will be obvious that their collaboration was ineffective and none of them deserve all of the points for that question. Some members may choose not to collaborate and be better or worse for it. But, based on how you've presented this, it would seem it's just a matter of whether the answers are correct or not.


As a grader, if not otherwise constrained by the lecturer for the course, you should be free to assign marks based on how much you feel the student understood and conveyed accurately the solution. In almost all pieces of written homework I've seen so far (mathematics), it has been easy to distinguish between those written by students who understand and those by students who don't. Especially those who copy tend to make serious logical errors elsewhere.

I am particularly strict with omission of key deductive steps when solutions to other problems show incompetency. Accordingly, you can give the bare minimum marks possible, marks which you are certain that the student deserves. And then you can tell students that if they feel they deserve more marks they are welcome to come and see you to explain their solution in person. By doing so, you simultaneously provide unbiased grading but the face-to-face interview for those who dispute the initial grade allows you to judge more accurately the deserved grade. Usually the students who do not deserve more marks will not be so daring to come and pester you.

  • I'd have to take exception at "t has been easy to distinguish between those written by students who understand and those by students who don't". That is just too subjective. Besides, it may be that who wrote the answer did understand, but they aren't the one handing it in.
    – vonbrand
    Commented Feb 17, 2020 at 18:11
  • @vonbrand: I've been teaching mathematics for a long time and I stand by what I said. And nearly the whole second paragraph deals with the harder cases. In my experience, students who really know their stuff will almost surely dispute their grade if they felt it was unfair and they are explicitly allowed to dispute it. As for instances of cheating, that is why I said "I am particularly strict with omission of key deductive steps when solutions to other problems show incompetency.".
    – user21820
    Commented Feb 18, 2020 at 1:53
  • I am addressing exactly the case stated in the question: "close enough that one student or another is being a parrot and does not totally underst[an]d what they are saying.".
    – user21820
    Commented Feb 18, 2020 at 1:53

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