There is a format used to write an excuse absent letter. You need to date and address the person you are proving the information to. Make sure that your name and the child's name is in the letter. Include the dates of absences. Most important include the reason for the absence along with any doctor notes if applicable. You can view an example on how to write an excuse letter by visiting:
. http://www.docstoc.com/docs/1413582/How-to-Write-Excuse-Absent-Letter