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?
A bigger picture may be; why is sending kids home for break with homework. It is my opinion, that people learn better when they actually have a break during their break. in my opinion, this is a tactic to prepare kids to think its normal to work all the time. That breaks are never actually breaks.
See edit please