Simply replace the unfilled areas such as "" and "[date]" with your information.
It has come to my attention that there is a serious problem between my [son/daughter], [Name], and [his/her] fellow student, [Name]. It is a situation that needs to be immediately addressed.
[Child] has come home several times this [time interval] complaining of [complaint]. [He/She] has told me that [Name] has repeatedly [action resulting in complaint]. [Child] is so upset by this [complaint] that I worry that [he/she] will begin to fear going to school. I know neither of us wants that to happen.
Please let me know what we can do to stop this from happening to my child. If I need to come in for a conference, perhaps with [Name]'s parents, I am more than willing. I will expect to hear from you shortly.