Remember that Most Teachers Are Sensitive
Teaching is an intensely personal job -- teachers are people who are paid to care about the thoughts and feelings of others. Tact is likely to be more important than if you were talking to, say, a used-car salesman.
Good teachers welcome dialogue with parents because it gives them a better understanding of their students. Parents have the right to expect periodic updates from teachers and timely notification of academic problems. Remember: In the parent-teacher relationship, like most others, communication is the key.