Regarding bullying, at what point do I need to get school or other parents involved?
I would say it's always a good idea to let teachers know what's going on. They have very busy lives. They are keeping track of a lot of kids and they have a tough job. They are in it because they love kids. Information from you can be helpful. As long as you aren't accusing the school or accusing a teacher, I think it's a great idea to call and say, "You know, my kid has indicated that she's on the receiving end of some bullying type behavior and this is what we'd asked her to do about it. Would you check in with her too and see how her plan is working?" Or, "Would you let me know if you think he's doing better or what's going on?" Teachers will help you with that. They appreciate knowing that you're on it, that you view them as a partner as well.
