I told this story before, here goes again. In SE Texas, my 7th grade history teacher had a slide film for us to watch about the Northern version of the "Civil War", including Lincoln freeing slaves. Mrs. Halliday was evidently not in favor of the film and she had something else to do, so she asked me to run the projector and left the classroom. I sabotaged the film by keeping the slides way out of sync with the sound. It was impossible to follow the content and no one ever said a word about it. God bless you, Mrs. Halliday.