Is it legal for your employer to tell you to quit?

I am a teacher at a daycare. A requirement is going to school. I am currently taking my last three courses for an associates degree. One of theses courses require a 160 hour internship. Since my center offers pre-k I opted to intern in their pre-k program. They agreed and signed off on it. Illness, cms schedule, and other factors has affected this and I am short hours. I have asked for more time and was refused. I ask to work part time because of school and having a child with a disability and was told basically work 8hrs or find another job. I use my lunch break when i can, i started coming in at around 7am even though my schedule isn't until 9 to get my hours. I have a assignment that requires a 40 hr week among other requirements. I was told I can only use the time I already was given. Yesterday the owner asked me what my plans were stating she was asking all employees. I told her finish school and work within their pre-k program. Today I was told that I should basically just quit.