If you develop a course for a school, do you own the course or does the school? https://news.nurse.com/2015/07/29/legally-speaking-online-courses-ownership/
I can't think of an exception where the school does not own it. Even though you created it, you did it on their dime. They, thus, own it. That said, unless you created some really unique stuff, I can't imagine it would be hard to re-purpose what you've done into something else.
