Maintaining our composure in the face of adversity (i.e. when students push our buttons) is crucial! Exhibiting an emotional response, such as anger or sadness, is a reaction that should not be used more than twice per year with any group of students. I know what you're thinking...
Teachers should avoid emotional responses to misbehavior because they "may be dealing with someone who is seeking power through their misbehavior" (Sprick, 2009). According to Dr. Sprick, angering an adult can be a powerful reinforcement for this kind of student.
If teachers overuse the emotional response strategy, it will lose any power it may have had. An emotional reaction will impact students only if they rarely see it. If students are used to seeing their teacher get angry repeatedly, they are more likely to think, "There she goes, again!"
Avoid any verbal or nonverbal signals that indicate your negative emotions. We don't want students knowing that our blood pressure is rising, we're feeling feeling flushed, or beginning to stress-sweat.
Why? Well, from my experience, some students may believe that the teacher's anger leads to task avoidance down the road. Any time spent in an "emergency class meeting" or a "life lesson chat" is less time spent on instruction. In my classroom career, I've wasted hours of instructional time trying to convince the class why they needed to "turn their act around."
We must also consider the students who have not misbehaved. Have you ever had a student feel bad for you and apologize on behalf of the other students? It's likely that this student is also feeling anxious- and isn't in the best position to learn. In the worst cases, these students lose trust in their teacher's ability to "handle" the classroom and may 1) attempt to "fix" the situation themselves, or 2) emotionally/physically "check out" to avoid the stress.
When responding to misbehavior, it's best to be brief and fairly business-like. We must make it clear to students that it's easier (and more satisfying!) to receive positive attention from their teacher.