Trying to become a fapstronaut, but in a "life drawing" class

So I really need to join this community. This year I decided enough was enough. Here's the problem. I'm in an art class that focuses on the human form. Every class there are nude models to draw. It's usually clinical(no urges), but the problem arises when I'm trying to start a streak(my best is 3 days). I start wigging out in class, getting really distracted and ultimately failing to stay focused. My solution thus far has been to PMO to keep sane. This is not ideal I realize. What should I do? I will not drop the class, because it's making me a much better artist and I need the credit. Help!