How do you feel about a 13 year old watching an R rated film in school?

Glory

The permission slip reads as follows…
“I am having your student view a video called “Glory” starting Friday that portrays a very vivid picture of what a group of black regiment soldiers endured during the Civil War. I believe this to be a significant learning lesson for your child but want to inform you that it includes some adult situations and language. The mature scenes consist of some graphic scenes from battles and then some otherwise vivid word usage. That being said, I believe that your child will uphold outstanding character in viewing this video and will demonstrate a mature demeanor when necessary. It is important to me for my students to view this video but understand that you may not wish for your student to view the mature scenes. Your signature below will be necessary for your student to watch the video. I will have a respectable alternative lesson for your child to complete in the media center in the event that you wish for your student to not watch “Glory”.
Thank you for your consideration.”

I noticed there was no mention of the rating in the permission slip.
How would you feel about your 8th grader watching this movie in school?