Not necessarily, although it might be difficult for math tests. In school we had one larger test in German where the teacher left us alone for 4 hours. What I

Not necessarily, although it might be difficult for math tests. In school we had one larger test in German where the teacher left us alone for 4 hours. What I noticed was that we did collaborate to some extent – we shared and discussed ideas. But since we had to write an essay with our interpretation of some piece of literature there wasn't much possibility of "cheating" per se. Simply copying the text from another would not work and copying their ideas outright wouldn't either. And to get at least something of decent length there wasn't the option of fooling around for three hours either. Granted, this was in 11th grade, so we were a bit older already. It may well fail spectacularly in other environments. The teacher knew us for a few years and trusted us, and it worked out.