GQMedic once bubbled...
I can understand your enthusiasm about your class, but, realistically, work is work. It should be no question. If you have to put the class off due to work, then, put it off until it IS workable in your schedule. You may want to ASK your boss if you can have the needed days off for a class and simply not elaborate. Employers tend to respect classes and such, albeit it's not exactly a math class at your college, but you need not mention that. Otherwise, the class will need to wait. Be responcible and sensible.
Being responsible and sensible has nothing to do with work. Work will always be there. You think your employer gives a crap what you want? Or is looking after your best interests? Forget work and take the class. Work will always be there. In fact, one of my favorite sayings used to be "I was looking for a job when I found that one!" I cant remember how many times when I was younger that I wanted to do something and called my boss and told him that I was going to do this or that and when they tell you that you wont have a job when you come back then so be it, go find another. And if you are that valuable then they will make accomodations for you and you will still have a job when you come back. Life is short, dont spend it working for nothing.