Story, first published: Galaxy Science Fiction, July 1953

The alien missionaries of "Kindergarten" (Galaxy, June 1953), observing Earth disguised as vending machines, set up a huge, invulnerable building on Peter Chaye's farm. (Chaye is dying of cancer, but the aliens cure him.) Peter and his girl friend feel compelled to enter the building. The military, making their customary paranoid response as if these aliens were Godzilla, unsuccessfully try to stop the couple by destroying the building with an atomic bomb. The huge building is a "school" for humanity, and Peter and Mary are among the first "pupils". The aliens have come to reform humanity by sending us back to school, and our "graduation" could lead to eventual acceptance into the brotherhood of the galaxy.

Ewald, Robert J.: When the Fires Burn High and the Wind is from the North, p.60