I saw a post last night whilst lurking about someone wanting to thank their DC's teacher etc and I can't seem to find the thread anymore, plus I didn't have time to read all the responses so I thought I would make my own thread.
In secondary school is it the norm to send emails here and there to thank teachers who have helped your DC? I ask this because I have a DS in year 9 who laughed when I asked him if he wanted me to write a nice note to his form tutor who has been really lovely and supportive over the year. So I suppose that won't be happening 
But I do have a DSD in Y7 at the same school and DH wanted to send her form tutor who also has been lovely and very, very helpful this year. She's supported DSD through many issues, etc and really has gone above and beyond. DS told DH that he shouldn't write an email as if DSD's classmates found out, they would have a laugh at her.
So AIBU to ask what is the etiquette for thanking teachers in secondary as DH and I aren't too sure to be frank
It is very different from primary to be fair!