I gave my students a take home exam over spring break. (This is normal where I teach) One of the questions was particulary difficult. It came down to a factor of three in the solution. That factor inexplicably appeared with no justification on many of their exams. I intend to have the students I suspect of cheating come to my office to solve the problem on the board. What would you do?
Edit: I gave them the Tuesday before spring break until the Thursday after. I didn’t want it to be right before or right after.
When I say normal I mean giving take home exams.
The edit really makes it seem like you’re entirely missing the point everyone is making.
Just don’t be accusing anyone of cheating. It really seems like everything you did would have made it seem to any reasonable person like copying answers from any source was allowed.