The one that sticks in the memory is Roman Polanski’s Macbeth when we were about 12. It was an uncut version, and the teacher did warn the class that it was quite a grown-up film. It was a huge, huge success.
(snap, tellyworth! 
)
We very rarely watched movues in class.
There were a handful of times that we went on a field trip to Manhattan to see a moie at Radio City Music Hall- we saw ***Sound of Music, Dr. Zhivago, Mame ***and Godspell that way.
Among the few movies I recall watching at school… To Sir With Love, The Diary of Anne Frank and Abbott & Cpstello’s The Widow of Wagon Gap.
In elementary school, we all went to the gym/auditorium/cafeteria to watch Pollyanna, for no apparent reason. And considering that all the students had to sit on the floor, it was especially dickish of them to choose a two-hour-and-fifteen-minute movie. At least The Red Balloon would have been shorter!
16mm versions of 7th Voyage of Sinbad
Original The Thing
Forbidden Planet
Some Disney Educational shorts
It is indeed. Here it is.
Song of the South. There were several others but this one stands out to me more at the moment.
I remember from elementary school in the 70s…
Pollution
And one I can’t find on youtube called Patch the Pony about avoiding strangers.
Our movie society played ‘Plan 9 From Outer Space’ and ‘Bucket of Blood’ for some reason, movies that were chosen by the pupils themselves. Probably couldn’t get away with that sort of thing nowadays.
Legend of Sleepy Hollow – the Disney cartoon – shown during elementary school music class plus my Sunday school Halloween party every year – scared the bejenkies out of me.
Danse Macabre – film strip also shown by my elementary school music teacher every Halloween – also scared the bejenkies out of me
Born Free
Free to be You and Me
Red Balloon
Donald Duck in Mathemagic Land
lots of Disney educational shorts
Little Big Man
Excalibur
Jr. High and High School, the ones that I can remember are.
Flowers for Algernon
Finian’s Rainbow
The Music Man
7 Brides for 7 Brothers
(there were more musicals, I just don’t remember them)
Elementary
The Raven (the 1963 version)
Zulu
(don’t know what they were thinking with the Zulu one).
I hardly remember any “entertainment” films at all, even on dismal winter days. The strongest memory I have of an educational film isPhoebe, a National Film Board of Canada classic about a teenage girl who fears she’s pregnant.
The boys and girls saw separate films in Health but we all watched how to drive a tractor on a hill. (You go around and around.)
The Living Desert and The Restless Sea are the first two that come to mind.
I remember in 10th grade, near the end of the semester, the English teacher showed us Batman (Burton/Keaton version) to keep us busy while she graded papers.
Free to Be You and Me
Red Balloon
Romeo & Juliet
And a filmstrip, The Cheetah.
My piece of “The Red Balloon” trivia, since the film has been mentioned here several times… the director of the film, Albert Lamorisse, also invented the board game Risk.
Paddle To The Sea - wow, blast from my past! 
The Red Balloon
The Good Earth
Once, they sent the boys out and showed us girls Walt Disney’s The Story of Menstruation. We must have been ten or eleven years old at the time. It was just vague enough that I didn’t “get” it and went home and asked my mom what the heck it was all about.
Here’s one I think I remember from 10th grade biology. Tragedy of the Commons. Though I don’t remember the discussion of birth control pills in the sample clip, the description sounds like right. Doesn’t look like the full version of this one is up on youtube or archive.org.
I always get that one confused with Fantasia.