OK- I am a "kill 'em with kindness" person. Nothing makes a irritable person more uncomfortable than a smiling, sincerely happy attitude. Two suggestions- #1 Give her a Christmas present - not a gift card- which will benefit the kids not her but with a happy, upbeat note. "Since this is Tommy's first year in school and he is learning so much, he wanted to send xxxxx. We are looking forward to a happy holiday and wonderful new year". OK notice- there is no mention of "Thank you for all the things you have done" - there is no "Tommy has enjoyed being with you" etc. BUT there is a present and note. I would give her one month after the holidays- any chance you can volunteer? after the holidays--if things do not improve then I would contact the principal and say I want him moved now. I would also not discuss this issue in front of my son. Good luck!