Sorry for whistling in class............

Dear Mr.Wan,
I am sorry for whistling in class. I really did'nt mean to whistle and I fully understand that it is a bad habit to whistle in class.

I know that if I whistle in the class I will disturb the class if I whistle in the class. I did it unintentionally as I was giving out the papers and I have just learnt how to whistle and it has became a habit. I know that whistling is a very very very bad habit and I will do my very best to kick the habit for good. I assure you that this will never ever happen again. I apologizes for wasting 30 minutes of your lesson time.

I sincerely hope that you will forgive me.