. Improvement is temporary.
Yelling only works in the moment. Like a playground bully, it’s used to intimidate students into compliance. The only reason why it works is because the teacher has an unfair size and/or authority advantage.
2. It doesn’t change behavior.
Behavior only changes when students want to behave better–which is the result of strict accountability combined with a teacher they like and trust. In the end, yelling causes more misbehavior, not less.