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.