Origin

This character combines a component meaning "ripe" or "mature" on top with earth or ground at the bottom. The idea is that a place where knowledge is cultivated and ripened—where students mature intellectually—is what a school, particularly a cram school, represents. The earth radical at the bottom classifies this as a place or building, much like many characters for locations and structures. Over time, the character came to specifically mean a private academy or tutoring school where students intensively develop their skills and knowledge.