Comment by aerostable_slug

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.