In my differential equations class my friend went to hand in his test, he goes to put it face down on the pile and only then noticed there was a backside to the page.

I’ll never forget the look on his face, but also, he was a good student and super honest guy, so the prof took pity and he passed the class.

That prof was kind of a dick, he basically treated the undergrad class as a pipeline to find grad students, so he’d throw a ton of stuff he hadn’t taught you on to the tests to see who he was interested in. The classes were just examples on the blackboard for the whole class too.

I got a decent grade, but he failed to teach me a strong intuition and so much of that knowledge is lost.

I’m still proud of some of the tricks I came up with during the tests though — there was a lot of “I don’t have a calculator, these are incredibly annoying numbers, either he hates us or there a trick” moments… and there usually was some trick that you just had to figure out live on your final test worth 60% of your grade.