They transferred to Hogwarts.
Back in the Eighties, there was a British TV situation comedy, “Yes, Minister”, that had an episode about a similar situation involving a hospital. The confrontation between Hacker and Appleby about this was one of the funniest bits of dialogue since Restoration Comedy.
The one room schools on the islands here sometimes have 5 students, sometimes 1 and sometimes 0. When the school population is zero, the school has to technically stay open as the process to restart a school is a pain. (This is on the several very small islands with year round populations in the 2-4 dozen range.)
Gotta keep unemployable Liberal Arts majors employed as teachers.