Well it's tricky, but the Affordable Care Act puts a limit on how many hours part time workers can work without the employer paying for insurance. For teacher this arbitrary number is 12hrs. So I can spend 12hrs/wk in front of students. If any of the part time workers go over that 12hrs/wk, then the employer has to pay a fee (so many $1000's/employee they have - I don't have the #'s in front of me, but for our school it would be a $1million+ penalty if just 1 employee goes over the limit). At a community college, 85% of the employees are part-time, so you can imagine that they couldn't possibly come up with the funds to pay insurance for all those employees that weren't previously covered. And of course I'm under my husband's insurance, so I don't need insurance offered to me anyway.
In any case, at a college you teach per semester, not per week. My husband teaches at a high school, so I am able to teach nights and summers, since he is home. In the past I taught full time in the summer and also could teach intercessions, which is a condensed semester of 4wks. But the ACA doesn't care how much I work per year, but per week. I can teach a course in a 16wk semester and I am only in front of students 9hrs/wk. But in the summer or intercession the same class is taught in fewer wks, so I am in front of students more than 12hrs/wk.
So the colleges around here have all cut hours and hire more part time employees to make up the difference. I have many friends in other part-time jobs who have had the same problem.