Dear [Head Teacher of Principal]
Resignation from post of teacher at [Name of School].
I wish to confirm that I am resigning my post of [Your Teaching Role] at [Name of School] with effect from [Date of Resignation]. My last date of employment will thus be [Date, check against term dates], and my last date of attendance will be [Date of last day of term].
I would like to thank you and the rest of the teachers at [Name of School] for the support that you have given me throughout my time here. I have enjoyed working as a part of this team, and appreciate the opportunities that I have had for personal and professional development.
I shall ensure that my remaining time working with the students of [Name of School] will be as successful as the earlier terms.
Yours sincerely,
[Your Name]