A couple more cents' worth...
--For the record, I oppose legislation or constitutional amendments making it a crime to burn a flag--assuming it's not someone else's flag. Free speech means just that--if we start making exceptions, there will be no end to them.
Still, it would not be a wise move to burn a flag in my presence.
--If any of this story is true, this teacher should probably be fired, not for flag burning, but for being a lousy teacher and filling kids' heads with crap.
--However, whether he is fired or not should be left completely up to the local school authorities.