I tend to be very careful about books I use in class. I have "kid" books, which are out and available to the kids all the time. I do not use nudes as examples in elementary, however, sometimes in videos or in books (like the Mike Venizia series) there are "sort of nudes". We have the discussion that the body is great and that artists study the human body because we all have one <smile> and because it is the most difficult subject matter to put into one's artwork.
On the other side, I have lots of books I pull visuals from (either make copies or hold open the book) that are completely in appropriate for the children to have access to. These books are in a reference book section far away from the other books. Often I have parents looking at them or other teachers borrow them, but I do tell parents they are there because there are some works that are not appropriate for this age level.
My question would be:
#1. What was the visual?
#2. How did it reinforce the objectives you were teaching?
#3. Could you have chosen a different work to teach the same objective?
If you had to use this work, then I would make sure that you can back up the use with valid reasons. There is the idea that art is art and they would see the same thing at a museum. But I always work from a very conservative point of view when I am showing works to students. In a museum, a parent can make the choice to not take their children or not view that particular work, but in school, we do not want to be censored by others, so we need to be conservative in our choices. Espeically these days.
That may seem like the coward's way out, but I know as a parent, I want to have choices about what my children are exposed to and when. I would want to know that at school they are safe and not uncomfortable about what they are exposed to.
In the end, your principal can pull whatever he/she wants!!! So, if you feel some piece of art of literature is valid, you had better be able to back it up with hard data!!!