I think the teacher should be comfortable with what they teach. Plus, you have to consider the fact that while you may be all right with your children being taught "uncensored" history, other parents may not. Yes, some people are very emotional, and yes the school boards tend to like to avoid having to deal with over sensitive and overprotective parents.
I think, Magickz, that if you want your children to know everything, you should be prepared to fill in the blanks that the teachers leave out, because, like I said earlier, the school boards are just afraid of teaching something that other, over sensitive, parents don't like, and don't want having their children taught in school for whatever reason.