Every once in a while, a student will feel the urge to cheat in a written exam because s/he did not study hard enough.
Imagine this: the day before the exam, you have no time to cram everything in.
Therefore, you print out a cheat sheet, and tuck this into your underwear.
During the exam, you look at all the questions and see which ones you can’t remember.
Then you go to the toilet, JUST ONCE, and inside the cubicle you take out your cheat sheet and look at the relevant portions.
How would the examiners ever catch such a cheater? Perhaps multiple people have survived their exams like this?
I knew a girl in college who used a similar ploy. She wrote her cheat sheet on her thigh, just above the knee. If she saw the monitor come walking around, she would, with a show of indignation, pull her skirt hem down over her notes.
Best way to combat - make the test extra hard and open book / notes
I had many testes which were open computers (Electrical Engineering - we had to do SPICE runs and such)
The bathroom trick has been around for decades if not longer. That’s assuming the teacher will let you go to the bathroom.
I had a prof at university who had a rule that if you left the test room for any reason, then your test was finished. She really took cheating seriously, didn’t give a flying rat’s ass about the honor code, and usually caught someone taking the test for someone else at least once a quarter.
I had a take-home Calculus final exam once. It was given out just before the winter break and collected just after, so we had a whole week to do it. And it took all week too!
The rules were simple: We had to sign a statement promising that we had not received any outside help with the test. But it was entirely open-book.
(I found one of the problems, verbatim, solved and worked out in full, in my Calculus book from the previous semester.)
I’m not even taking an exam anytime soon.