"I just wanted to send a note telling you what a wonderful tutor Mark is. I have not had the chance to thank him personally yet, but John got an 800 on the math portion of his SAT.  I am sure this couldn’t have happened without Mark’s help. 

 I know my son is not always the easiest kid to work with...this is even more of a testimony to Mark’s subject mastery and teaching skills. I felt I should let you know just how terrific he is."