[Your letterhead, if desired; if not, your return address]

[Date of letter-month, day, and year]

[Recipient's first and last names]
[Company name]
[Street or P.O. box address]
[City, State ZIP code]

Dear [recipient's name]:

Thank you so much for providing my son with tutoring assistance related to his French studies. Because of your help, he is earning better grades and enjoying French classes so much more. It is so encouraging to see this progress.

We will be in touch soon to schedule more tutoring sessions. Thanks again for all of your help.

Sincerely,

[Signature]

[Sender's first and last names]