Announce and clearly state in the syllabus expectations on side conversations, interruptions while others are talking, tardiness, and other student behaviors. In order to help motivate students to follow ground rules, explain the reasoning behind the rules. If you have not taught before, you might want to read guidelines established by experienced TAs or faculty members. Also, you might reflect on your own classroom experiences to determine behaviors you find disruptive. The more defensive and hostile the teacher becomes when confronted with a disruptive student, the more likely it is that the hostility will escalate.
Effective teachers learn to respond calmly and to defuse rather than increase conflict.
Before you begin teaching, consider what kinds of comments in particular make you defensive. Self-analysis of your pet peeves can help prepare you to keep your composure during confrontational classroom situations. Referring to the established ground rules. If a student makes you so angry that you lose your sense of objectivity, tell that student that you will discuss the problem outside of class at a later time. You should not use valuable class time to reprimand a student with whom you need to speak individually.