Appropriate age groups:
Preschool and Younger
Elementary School
Middle School
High School & Beyond

General purpose of letter:
So, your child lost the important permission form for the field trip on Friday, wich MUST be handed in by tommorow? Never fear, just follow these guidelines.

Sample letter:
Dear _______ (teacher's name),
_________ (your kid's name) is allowed to go on the field trip on ________ (date of the trip) to the _________ (place of the trip).
Sincerely, _________ (your signature)

Other suggestions and comments:
You can also play around with it or add things, such as "I have enclosed the $3.00 needed" or "He has his own skates and I can drive 4 kids."