What to write as a thank you YR 2 teacher

[Pukkapadcrank]

Looking for some help and thought this might be best place to post.

My son's YR2 teacher has been amazing this year, she has gone above and beyond to help him and his classmates in many ways and I want to write to the Head to say this.
I would hope that she may be able to use this in some way to evidence pay scale point increase, although I am not a teacher so I am unsure if that can / would work.

I think this is her second year teaching since she qualified.

Any tips / suggestions are welcome. I was going to keep the letter factual with examples of what she has done.

I'm not a teacher, but when my DD has had a good year with a great teacher, I've not written specifically to the headteacher, but have written to the class teacher, giving specific examples of how they have gone above and beyond - and sent a copy to the headteacher.