Why do schools have a minimum amount of school days if you’re not like . . . Doing anything

Why do schools have a minim amount of school days if you’re like . . . not doing anything? Next week is my last week of school and I don’t have any finals, the end of the grading period was yesterday, so like . . .what’s the point? My last day is on Thursday btw. Anyway this is just just kinda random.

-Viridity