To, The Principal, [School Name], [City]
Date: [Date]
Subject: Application for leave to attend a family function
Respected Sir/Madam,
I am a student of Class [Class], Section [Section]. A [function, e.g. wedding] is taking place in my family on [date], and I need to travel with my parents to attend it. I will therefore be unable to attend school from [start date] to [end date].
I request you to kindly grant me leave for these days. I will make sure to catch up on all lessons I miss.
Thank you.
Yours obediently, [Your Name] Class [Class], Roll No. [Roll Number]