"Sir, I am wondering how it was that you came to that conclusion on that matter. Would you please enlighten us? As it stands now, I must disagree with you."
"Dude, you're full of shit. No fucking way!"
Much disrespectful questioning of authority would be perfectly acceptable if it were phrased more politely.
Then, if someone's worldview of authority contains as a clause, "No one must question me, ever", then there is no possible way for that person to be questioned without challenging their authority, no matter how polite the phrasing is.
I think it's perfectly possible for a teacher and student to have a disagreement, where both parties know that they disagree, and for the student to abide by the teacher's judgement while in the context of the academic situation -- as long as both parties are polite about it and recognize the right of the student to think whatever the hell they want, and the authority of the teacher to dictate educational format.