Dude, how can you even ask this question. And how can you people give this confused person such awful advice. The girl is a '5' and you are considering making a move on her?!!!
Real men wouldn't settle for less than a 7, even when desperate. I don't even rank below a 7. When my friends ask me to rank a girl like that, I just say 'Below a 7'. They all know that means "No way, Jose".
Aside from the fact that sub-sevens are DISGUSTING people, it hurts your chance of getting with a attractive person. Imagine you saw some girl, even one above a seven, and then found out she slept with some loser. Would you want her? Not me.
And don't buy into that whole 'practice makes perfect' nonsense. The psychology of sub-sevens is completely different than the psychology of useful girls. It's like saying you are going to set up mousetraps because you want to practice hunting men (the most dangerous game of all).
The proper approach, assuming things are as clear as you make them, is to complain to the professor. It makes you seem like you have integrity, suggests you are desirable, and may improve your grade.