Here's an unexpected cultural difference for you: laughter.
My students laugh at me all the time. They laugh when they're nervous, they laugh when I say something funny. They laugh when they don't know the answer, they laugh when I try to explain something in French.
Isn't it rather cruel, or is that just teenagers?
My American kiddos were always to petrified to say anything out of turn.
My Austrian kids were always so serious, except for the one jokester (der Spassvogel). There's one in every class.
Laughter makes me nervous. Laughter makes me sad.
I wish I could laugh back at my students, but someone has to be the professional in the room.