Complex sentence: Girls and Boys basketball has been the driving force of Oliver Springs's emergence as a small school athletic powerhouse that routinely beats schools with enrollments double and triple it's enrollment of 500 students.
Split into simpler sentences: Girls and Boys basketball were the driving force of OSHS's emergence as a small school athletic powerhouse. The Cats and Lady Cats routinely beats schools with enrollments double and triple OSHS's enrollment of 500 students.