Modeling nude for an artistic purpose it's a liberating experience, as women we encounter a lot of issues with people that cannot look at the human figure with respect and admiration... that's what you are gonna find when you pose nude in front of an art class. Also, when you see the final results in the drawings, paintings, or sculptures inspired by you, you can tell is nothing vulgar or pornographic but a Beautiful impression of your body that will last forever. However, posing nude in front of a class is not as easy as it sounds. Artistic poses might be uncomfortable, and demanding. You need to have at least a basic level of strenght and concentration to hold still for a long period of time. Being still is essential. It's gonna be cold... Just the fact of being still affects your blood circulation making you really cold.. You can manage this by practicing clearing your mind staying still in simple sitting, shoulders back, head up, trying to be as tall as you can. I don't think you will have any problems as long as you r comfortable with your body.