I am the Organic Chemistry Lab Supervisor/Manager and a teaching associate at the University of Maine. We teach 14 lab sections each semester and two accelerated courses during May and June. It's my job to make sure the proper chemicals are in the lab for each lab session. I set up the chemicals, keep them stocked, swap out the chemical boxes for each week's labs, manage the waste, keep records, ordering, keep the labs clean and running, maintain equipment, etc. During the academic year I also teach two lab sections, so that's 8 face-to-face hours every week, plus writing pre-lab lectures and quizzes, office hours, email consultation, and grading lab reports... endless, endless grading, about 16-20 hours a week of grading.
Summer session is different. Same responsibilities, different structure. We teach o-chem 1 in 4 weeks in May, followed by o-chem 2 in June. I teach one lab section of up to 12 students, with 3 different experiments a week... and still all the other responsibilities and grading.
I like my job. I am not a chemist so the first few years were challenging. However... I have a lot of flexibility in my time. I have to be on campus when I teach, obviously, and also in the chem building when the other labs are in session (in case of emergency, replacing/refilling something, etc.) and for meetings, but other than that, my time is my own, so I can grade and work from home, over the weekends and evenings if I need a day free, and even remotely (so on vacation or when I visit my sister, for example, and if I work while away I don't have to mark out the vacation hours). Summer is especially nice, as once summer session is over (July 2nd this year) there isn't much for me to do until mid-August, and nobody is ever looking over my shoulder. The grading is monumental and mostly frustrating, but the flexibility in the job makes up for the challenges of the position.