B.M.
Hi,
What basic right is being taken away? I'm not sure you can change this, but I would explain your reasoning to the principal and ask her if they could clasp their hands in front instead of in back.
Teaching uniformity is not a bad thing, especially if it maintains order - which is really important in the school. It's way easier for kids to stop themselves from getting into trouble if EVERYONE is doing the same thing- rather than just singling out the kids who can't keep their hands to themselves, they are providing a solution so that no one gets in trouble- heading it off at the pass, if you will.
I don't agree that the teacher should have to do this - the teacher is probably walking backwards, issuing direction, opening doors etc. One of the things kids learn in elementary school is how to behave in the way that's asked of you... even if your "boss" is not behaving in the same way. Get's them ready for the 'real world' when they have a job and have to do things they don't want to do that their boss isn't doing.