I would be interested to hear more from those kids about why they reacted as they did. Sometimes people laugh because they’re uncomfortable. Or maybe they are not strangers to brutality and were neither shocked nor impressed. It could also be a dynamic ignited by one or two “thought leaders” in the class who reflexively mock what they know the teacher expects them to respect to gain cool points with their classmates. Sixth grade is its own special Hell. I’m so glad it’s far in my past.