That is one way schools have been prevented from showing it, the rating. One dad called talk radio and he was steamed that the movie was shown to his child who was under 17.
It is propaganda. Reminds me of when I was a kid and we had a visiting preacher who had been to then Communist Russia. He had smuggled out posters that he had made into postcards that he could easily carry with him to show to churches here. They showed Christ throwing up at the wedding where he turned the water into wine. Stuff like that, all making USA and Christians look really bad. I see Michael Moore as a Communist propagandist.
Luckily, the film has not been shown at any schools in my state and never will be.