I believe that letters of resignation aren't only necessary for when you're quitting your teaching job. I think that you should turn in a letter of resignation even if you are successfully completing your contract. By doing this you will eliminate any doubt as to why you're leaving; no one can say that you were asked to leave.
Your letter of resignation doesn't have to be complicated. You can tell them you . . .
- have enjoyed working with them.
- feel it was an great opportunity.
- were able to you to grow both personally and professionally.
- wish everyone the best.
- are leaving to take up another position / study / travel, etc.
- do not plan to renew your contract with them.
- will complete your current contract and fulfill all of your teaching and administrative duties. So therefore your letter of resignation will be effective after the last day of your contract, which will be X.
