Might be a bit late to this, but when I was in 11th grade I had an insanely oblivious math teacher. She was cool as fuck (also ridiculously hot) and never gave out homework, claiming it was pointless, and she'd much rather teach us in class and use quizzes to grade our progress. She was also always on her computer, paying very little attention to us while we actually took the tests.
But anyway, I was constantly drawing in that class. It was right after my double block art class and I was working on my portfolio for art college, which was much more important to me than some intermediate math course I had to take for credit purposes. So I never paid a lick of attention.
Luckily, I knew a lot of what she taught already, so the quizzes weren't too rough. But, uh, whenever they were...and i didnt know the answers...I'd just fold up the test and stick it in my sketchbook and never turn it in at the end of class. She never noticed. I did this maybe 5 or 6 times. It would have definitely knocked my grade down a few letters if I had failed them.
At the end of the year, she was counting all our incompletes and noticed I had a 5 or 6 tests missing. Being the easy going gal she was, she just assumed I was sick those days. I did tend to miss a lot of school.
She wanted to me come in during lunch for a week and take them then. She always went out for lunch so it was basically me and maybe one or two students making up missing tests in an empty classroom.
A buddy of mine is a math genius, so I handed him the stolen tests I had collected and he filled them all out for me without batting an eye. When I went to retake the tests I'd just copy all the answers he gave me down onto the new test form, place it on her desk, and then I'd go finish my lunch period.
I got a B in the class. She was very thankful I'd taken time out of my lunch schedule to make up the tests and told me I was a smart kid. I still kinda feel bad. She was really nice.
Tl;dr- I used to take blank tests home instead of doing them in class, i got my buddy to fill out all the answers, and then I'd use those copies as cheat sheets when I went back to retake them.