I will offer some thoughts about your situation.
First, it appears that you created the "start" of the questions, but you want any teacher to be able to edit "their own" set of questions, not disturbing the exact same question from other teachers. So you want to remove the central administration (i.e., editing) from this point forward.
If so, what I would do is to create separate question categories for each teacher, export the original set of questions, the import them into the appropriate teacher's category. Using this process, you are "duplicating" the questions.
My guess is, and I hope that I am wrong, that you will someday want to make a change to an original question and have this change automatically moved to all teachers' question. Nope, I don't know how you can do this after giving teachers their own sets of questions.