I read something about dealing with managers at work that said that it is important for employees to find what the bosses communication style was (in person, phone, email, paper note) and to mirror it.
It is just plain rude for the teacher and principal not to write back to you!
I talk to my children's teachers with a lot of different methods. At drop off, at pick up, by email, they are always responsive. I am always at the school, I am the one who offers to photocopy spelling lists, who organizes the Fall Festival, who re-shelves books in the library. I am probably at each of my children's schools 5 hours a week. My house is a mess but my children are being educated well!
My advice is to get into the classroom and be as helpful as you can. If you work, as the teacher if there is something you can help with from home. It really does make a difference!
