I'm not sure that the act of dissection is something a person concerned with animal rights should be worried about. The animal is dead at that point and can feel no pain inflicted on it.
I would agree that the teacher is being inconsistent in condoning the dissection of other animals but not humans, but I would suspect that the teacher believes this to be the case because they think humans are uniquely endowed with souls.
The last class you should give up is science! Science informs nearly everything in your life. You simply cannot have led a meaningful life if you don't investigate the nature of your existence, even if it is on the level of brute facts.