There are in fact a great many school room sized cells in the United States. "Dormitory" housing is the norm for a significant percentage of inmates in jails, prisons, and immigration detention centers (imagine a school gym filled with bunks and you're often not far off). To add to the school-prison linkage, many facilities have lockers as well, replete with padlocks that make dandy weapons.

That said, I am still doubtful there are 1:1 copies of jails being used as schools, regardless of visible similarities. I don't see any of these supposed jail/high schools with secured rec yards for instance, which generally make up part of the structure of the facilities that look most like the examples given.

I'm sure they make some modifications, but they started with the plans for a prison. The overall building footprint and architecture is the same.

Don't listen to this Ozarkian tweaker. He has been fed some fringe anti-education propaganda his whole life and chooses to maintain life inside a glass bubble.