a principal of a huge school once told me that sincere notes of appreciation mean the world to a rebbe or teacher…and evoke in them a desire to be kind to your child,too.
on a side note,after 2 checks FOR FIVE DOLLARS(j.c.tips) bounced(!!), I was so embarrassed, I decided…if I have so many tips to give I can’t even keep track…i’d rather give one normal size tip to the rebbe(who has to prepare even in the summer).