I like to consider myself a thoughtful college student. Not that I've never been tardy, and yes, my phone has gone off ONCE before, but I never do these things intentionally. I'm generally on time and pay attention. If I do glance at my phone, I try to be discreet, and I never just completely ignore classroom etiquette to eat, do unrelated homework or read materials not associated with the class I'm in (of course, smaller, informal-like classrooms are often a different story). So when I see people getting away with things like...
1) Playing games in class. There's this one guy who sits diagonally from me in my political science who never brings a notebook or pencil and is constantly playing Tetris on his iPod Touch. ... Why even come?
2) People who come to class LATE on exam days and jiggle the door handle or knock when they've been locked out. Seriously?
3) People who are just habitually late.
4) People who can't accomplish the simple task of silencing their phones.
... I sometimes feel a little frustrated. I don't know how most professors stand it, honestly. But was this Cornell professor did completely necessary?
Yawns happen. I doubt it was voluntary. The volume of said yawn probably could have been controlled better, but I doubt the student was actively try to disrespect the professor. Just reading the word yawn or thinking about the word yawn can spur your mouth into action. Didn't you just yawn reading that? And I bet you weren't even sleepy.