How do you approach resolving a situation where a teacher and your child are having a major conflict? When your child comes to you complaining about "unfair treatment" from a teacher, how do you identify where the problem is really coming from, without making your child feel like you aren't supporting them?
Here's one blog where a parent discusses his child's dissatisfaction with a teacher's approach to science lessons, and how he (the parent) dealt with that.
(I got that link from this answer: How do you handle a teacher that teaches pseudo science? )
It's not a great fit, because the teacher was in the wrong and the parent had law to back him, and a sympathetic head teacher. But the general approach seems sound.
There's a whole spectrum of solutions here, depending on how subjective the point in question is and what your personal opinion of the matter is.
First get the facts, if there are any. Assuming the matter is important enough (and rare enough), get the teacher's version too. Listen to your own gut feeling regarding who's (more) right. Now consider what outcome you really want from this conflict: sometimes a victory can hurt more than letting it go.
With regard to supporting the child, I don't think you would always take the child's side. The child is better served by learning that you are a just and fair parent because you take both parties' version into consideration. If you decide that the child is right, then throw as much energy into his defence as you feel fitting in the situation. If you feel the teacher is right, gently but clearly make him understand that the teacher is, in fact, right.
Seriously, read the book Counseling The Culturally Diverse (it blatantly puts out there the mass racial and socio-economical discrimination that still occurs today in very subtle and slick ways).
Teachers, counselors, ect. seem to try to act like the problem is in the child, when that's not always the case, and finally, its documented! Amen!
The book is by Sue and Sue; people showing how people like to take the easy way out. They like to blame the target instead of those really causing or contributing to the conflict. Its not always the kid. Then the parents are made to feel like its their parenting strategies (exactly like the "sweep It under the rug" comment above).
Stand up for your children at all times when in any doubt, and never assume. Question.
Be involved and always be sure before making assumptions.