Daughter Punished at Assembly

My teenage daughter attends the same high school where I teach. During a recent assembly, while all the other girls were seated on their benches, I noticed that she was the only one standing up at her seat in the middle of the hall. I was shocked but knew something had happened—her face blushed red with embarrassment.
After the assembly, I checked in with her and asked why she had to stand up. She told me that a senior manager had made her do it as punishment for talking.
Was it right for her to be reprimanded in that way? I didn’t think so.
As a teacher, I also sometimes have to quiet large crowds of teenagers during assemblies. I know how to hold their attention without publicly embarrassing a student who is talking. For example, if I notice a girl whispering to someone while I’m monitoring, I just move closer and look at her, and wait. She quickly realises and stops talking—without me saying a word or making her stand up. What likely motivates her to stop is being caught and the worry that the other girls around her will notice and look at her because of me.