My daughter (12) is in middle school and had a substitute teacher last week. According to my daughter, there were some kids in the class who were especially difficult towards the sub. It was bad enough that the sub took down all their names and sent most of them to the principal's office.
When the regular teacher, Mrs. P, came back the next day she saw the report with the names the sub took down and told the entire class to write an apology letter to the sub to be collected the next day.
The kids that were mean to the sub needed to write about their poor behavior, the kids who didn't do anything were told to write an apology for not stepping in and standing up to the 'bullies' on behalf of the teacher.