Address the complaint letter to a specific person. This could be the minor's teacher, principal, or parent.
Explain who you are. When complaining about a minor, use complete transparency. For example, if your child and the minor you're complaining about go to the same school, include this information.
State the purpose of the complaint you're writing very clearly. Be clear about the problem you're having and use plenty of details. For example, if the minor has been bullying your child, include specific dates that the bullying has occurred and what type of bullying it is.
Talk about the importance of addressing the issue that you're having with the minor. Bullying, for example, might be having a profound effect on your child that is harming not only school performance but your child's desire to go to school at all.
Include what you want done about the issue you're complaining about. Requesting a specific action by a certain date will make your complaint letter more effective. An example action is requesting a meeting with the minor's teachers or parents to discuss the issue in person.