Packing your books up and squirming about five minutes before the hour is over, especially if I am trying to lecture or conduct a discussion. I find this incredibly rude , as do other students who are trying to listen. It is better for everyone to be clear about things than to be confused, and what you fear might be a dumb question may be puzzling lots of other people in the class. Use e-mail or come to my office if you do not wish to speak up in class. Visits from students in my office, or e-mail messages.
Open communication is always best.
Expressing your point of view during class discussion. Although I have my opinions and political commitments and will not hide them, I try not to impose them on people during discussion. I may, however, argue with you, or encourage debate between you and other students to help sharpen issues. I feel the classroom is a much more exciting place if a wide variety of opinion can be expressed, especially if done so in a civil manner. Requests for special dispensations because of illness, handicaps, or devastating personal problems.