So, the principal said not to tell the teacher so there are no preconceived ideas. Then, contact the teacher during week 2, without giving a lot of details, try to see what the teacher's feeling is.
Am I the only one with alarm bells going off? This sounds to me like code. Rough translation: "This teacher is a rigid thinker and hates to be told things by parents. If you're lucky she might notice on her own, and then you can give her a gentle nudge that might help her along, but only if you're vague enough about it. Good luck."
I hope I'm wrong.