Do I need to do something about loosing my job?

I work for Kelly Services that helps people receive work from places like Coty, a factory in Sanford NC. I've been working for a year now and was going to quit in three weeks to focus more on schooling and eventually find a better job. Last night February 21,2017 at 10:58 pm. The manager called everyone for another one of his meetings or rather lectures. My department works from 3pm to 11pm on the dot. His lectures usually last about thirty minutes. I told him that I had homework to do and that I also had school in the morning and "I just don't have time for his meeting". He said "Ok, bye." I come in today and they're telling me I've been fired because of what I said last night. The representatives will call me tomorrow about what they can do but still... I can't afford to not work these couple of weeks, I need the money. I haven't missed any work days because of school either, so is this fair?