If this really bothers you and your kid, I would 1) ask the other 3 kids to learn what happened; 2) setting up a meeting with the teacher asking her how your kid is doing in school, with an attitude to learn how things were going. At the meeting, you may tell her your kid was upset about what happened at school and you are concerned. Do not accuse or try to tell her how to do her job. Instead, show your support to her. She would know what you want without you asking.