When I was in school, one of my friends was convinced the professor was changing her answers on exams so she'd not pass.We couldn't prove it for all exams, but on one test, an answer was erased and the same answer circled with red pen like he forgot to circle a wrong answer before marking it wrong....she got those points back....
Also, you have to be careful w/ white kids, even the ones who claim to be your friend. I remember for a linear algebra class, we had this huge midterm coming up, everyone was already struggling in the class, and the midterm was freaking folks out. I studied with this other black guy in my class, as the third of us (yes, there were only three) was out sick (he eventually would have to withdraw). So anyways, come exam day, these white kids, some of whom I never even saw in class before, are breezing through the exam and handing the professor back the exams with this air of cockiness that just didn't set well with me. So, once I finish, i head outside and I see some guys waiting for a friend in the hallway and I'm like "man, that was something," and I know they can't resist when they think they're holding something over you, so I'm just waiting for them to say something, and eventually, some Chad goes: "Nah, was basically word for word like the review session, just changed a couple numbers." so now I know what's up - "oh, there was a review session, didn't see any email..." and then they kinda get quiet cause they realize they weren't supposed to talk. "Oh yea? Some kid in the class organized it...I just heard about it, don't know if he ever sent out an email...said he would though" but I'm not dumb...never intended for the whole class to be invited and the professor sat up there, in a study room full of white kids and didn't think to send out an email while in the middle to ensure the entire class knew....
It was alright though, sat behind some Korean kids who managed to take a cell phone pic of the exam and answer key during office hours supposedly. Checked my answers against his and coded with my friend so he wouldn't slip behind. Both of us ended up with B's.....
ETA, main point was that the other black kid in the class, was supposedly friends with some of those dudes and they didn't think to invite him.