With due respect, I would like to inform you that my name is _________ (name) and I am studying in __________ (class/semester) having ___________ (roll number).
I am writing this email to request you to grant me permission for not attending classes from __/__/____ (date) to __/__/____ (date) due to ____________ (mention reason – competition/exam/sports day/other). I assure you that this will not affect my academic performance and I will cover my syllabus accordingly.
I hope that you will consider my request and approve the same. If you need any further information, please let me know at your convenience.
___________ (Roll number),
___________ (Contact details)