The common thread running through the literature about disgruntled, unhappy, angry students is this: communication. Most of the time, these students simply feel that they are not being heard, being listened to. Giving them a forum, whether during class or in private during office hours, generally resolves whatever conflict is happening within the angry student. The first instinct of the instructor might be to simply ignore them, and while this approach may avoid a public confrontation, it probably won't solve the underlying problem and allow the student to learn the material