The women is lucky the students are not sueing her failure to deliver on the paid for service (cancelling classes because she got a question in prior class).
I have taught at an Ivy league University for 31 years (undergrads, grad students and professions students in science/medicine). If your not ready to field questions and even challenges to points you make in a lecture...you shoudl not even set foot in the classroom.
You taught at this level for 31 years, and still don't know the proper usage of "your" and "you're"?
Sorry, could not resist...