I've taught HS kids for ~4 years so not quite the same demographic as yours. That said - and I know folks object to doing this - you have to play disciplinarian _and_ teacher. Set a firm culture around no phone usage and kick anyone out who uses one.
Kudos to you for going back to your alma mater and teaching. That's something I want to do, too.
That's another advantage of community college courses, is it may actually be practical to implement that sort of discipline. It certainly isn't when it's you and a TA and 100 students in a big lecture hall.
Kudos to you for going back to your alma mater and teaching. That's something I want to do, too.