Rotate the teachers between schools:
year one - suburban middle class
year two - working class
year three - McMansion resident class
year four - welfare recipient class
repeat until retirement
Just get rid of tenure; if the students don’t learn, the teacher doesn’t stay. Teachers have told me there are several obstacles (home life and such) to teaching some students; I then ask them why we don’t just have minimum-wage attendants guard the children for six hours per day.