However the other students immediately pointed to the line my advisor has to sign - where I put my advisor's name underneath.
Dr. Advisor, what's wrong with that?
Apparently, it's rude to say "Dr." when referring to your PI or teacher. The appropriate designation is Professor, always. In undergrad, all my teachers were "Dr. Rocket Power" or "Dr. Senior Capstone." Not so at World's Best School.
Well, goodness - and here I always use Dr. when I speak to Professors.
My advisor explained that he always gets that from students who went to school west of the Mississippi, which I did. I'm not sure why that might be - perhaps it's a slight against MidWest schools, that they like to emphasize who has a PhD? And everyone on the coasts already has a PhD, of course, so the higher designation is Professor?
How do you address your teachers?