In discussions for my online classes, I use an approach that I think is fairly standard: Students respond to my prompt and then comment on the responses of two other students. I have set it up so that a student must reply to my prompt before seeing other student's responses.
A student alerted me that the response of another student (to my prompt) is very similar to hers. I checked, and it is similar enough to NOT be a coincidence.
Given that students cannot see the responses of other students before posting, I am trying to figure out what happened.
I did come up with these possibilities:
1) The second student could have responded, submitted, read other replies, and then gone back and changed hers. However, her response is not marked as being edited.
2) Both students copied from another source. I did do a quick Google search of the replies, but found nothing.
3) The second student could have a friend in the class and looked at the discussion with her account.
I guess my dilemma is that I do think this second student should be penalized (via the discussion grade) for this, but am not sure how she did it.