Simply replace the unfilled areas such as "" and "[date]" with your information.
Dear [name of teacher/principle],
My [son/daughter] will be starting as a new student in the [grade] grade in [time period before child starts school]. I would like to take a few minutes to introduce [him/her] and our family to you.
[child's name] is [age] years old and is coming from [name of current school]. He is [list one quality about child: shy/outgoing/fun loving/etc.] and enjoys [list one or two things child enjoys].
In addition to [child's name], our family includes [list members of family].
We all look forward to meeting you and spending the rest of the year with you. If you have any questions, please don't hesitate to call. I look forward to being a valuable part of your school in the future.