The website Teacher Vision offers a free printable document with a sample letter and advice on how to approach parents about bad student behavior. The World Association of Technology Teachers website also has sample letters to parents for a variety of offenses.
As of 2015, Teacher Vision's website hosts a two-page document on how to alert parents to the need for disciplinary action against their child. The second page is a sample form letter with blank spaces for the child's name. The sample focuses on missing homework.
The website for the World Association of Technology Teachers hosts many such form documents for a variety of problems, including missing homework, fighting and poor behavior overall.