well.....I know that while I do not choose to show nudes to my students (elementary) they do see them inadvertanly via pop-ups on videos and when we go to musuems. I have an open discussion with them re: nudes in art. Also I once accidentally showed a male nude calder wire figure to my 4th graders...had the nude talk with them then went to my principal and told her. She said no problem. WE have very open puberty classes here starting in 5th grade...also in Kindergarten we have anatomically correct baby dolls for the kids to play with...so we are pretty open to nudity here when it is appropriate to be so.
What I will say is that with all this stuff re: Catholic Church and internet preditors....better to be safe than sorry!