We know, as adults, that not everyone is capable of getting along with everyone else. Different personalities clash, expectations are not always clear and so forth. Talk with your teen and come up with a list of things they could do to either improve his relationship with his teacher or keep it from getting any worse. Remind them that the goal is a good grade, not who is liked best by the teacher. Your teen should use respect when dealing with a teacher, always, but not take their attitude toward your teen to heart.
More tips for dealing with difficult teachers.