Which aspect of Act 2 of The Monsters Are Due on Maple Street marks it as science fiction and not fantasy fiction?

It is about aliens and takes place on another planet.
It is about humans who meet aliens here on Earth.
It is about aliens visiting Earth and observing humans.
It is about magical events that cannot be explained.

I agree to a extent. Not every teacher should be armed, only mentally stable, and trained individuals, and those who show their dedication to teaching, I would feel safer if I had a trained teacher with a firearm, because a shooter would find a way in and we cannot count on law enforcement to show up every time.