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.
Probably treating as “forgetting to write down their steps” before jumping to cheating; presumably you’ve been teaching them to show their work and they forgot to do that here.
Give them the chance to show you how they solved it on the board, if they can then great! Give ‘em the points and send em on their way. If not, then give them a zero for that part of the test and move on.