Rule The School Meaning

(idiomatic) (of one or a group of students) To socially dominate a school's student population, or a major part of it (such as the girls or the boys).

Example: To substantially control a school administratively, financially, or to control a school's curriculum.
1884, George Augustus Sala, “Westminster School”, Temple bar, volume 71, page 504:
  After Page, Dr. E. Goodenough ruled the school from 1819 to 1828. On his retirement he obtained the deanery of Wells ...
1847, William Edward Heygate, Godfrey Davenant, page 123:
  But as Shelley was by far the cleverest of the three head boys who were there, he ruled the school.