Number one rule: Do not alienate those you need to help you and your child!
Communication Is Key!
The role of the public school: it is so large, it has to have limitations. Despite the heart of the teachers and administrators to be able to do more, by law and with the realities of their size, all they are obligated to do is help the student pass. The system is set up to get students through it, not to ensure that each individual reaches their potential.
The private school: still a system that is age/grade based but each school has its own particular mission with their goals going beyond just getting kids through; their desire is to help the individual child.
The thing to grasp about any school is that it comes as a package. There are things you like about it and things you don't.
Have perspective: teacher’s intentions (usually good) and limitations (time, energy, lots of other children in the class)