Most of the movies we were shown in school were not good. Film strips reminded me of ViewMaster experiences, and the reels we screened were in general shot by mediocre camera people and narrated by patronizing voices.

That’s not to say the screenings weren’t memorable. There was something about the turning off of classroom lights that we all found a little exciting, at least compared to the usual environment. And the lucky student who got to run the projector, threading the shiny film around the pinball-like pegs until it caught and self-fed, stopping the machine in a hurry on those occasions when something stuck or snarled or burned or tore: that was a job we all wanted.

And some of the school movies were excellent. Leave it to Walt Disney …

I’m sure I’m not alone in remembering the Disney demonstration of nuclear fission. It took place on a billiard table I think. The surface was covered with mousetraps, and each trap was set with a pingpong ball atop it, when the unseen hand dropped a triggering ball into the system.

And that unseen hand! I get a little thrill even now, remembering how delighted I was when that hand wielded a magic pencil or paintbrush that created illustrations as it swept the screen.

Or what about Mr. Hemo? I loved the Disney film that explained the body as narrated by the blood.

I saw one memorable movie in school that was not created by the Disney studios. They made us watch it in Driver Ed class, and it was as amateur as any other driving class movie. But it was so simple and true that it was compelling.

It was called “Courtesy is Contagious.” It showed people doing regular everyday things around other people, and being polite. They weren’t just refraining from rudeness; they were actively courteous: smiling at passing strangers, holding the door for the person behind, reaching forward with attentive or helpful body language. And of course you saw, when a person experienced the politeness of the held-open door, that person turn, in turn, to see if someone was following for whom the door could still be held.

It was stunningly true. The movie didn’t point out how contagious rudeness is, too. It didn’t need to.