 The maximum tenure in office was nine years , but every three years officials were graded on their performance by senior officials . If they were graded as superior then they were promoted , if graded adequate then they retained their ranks , and if graded inadequate they were demoted one rank . In extreme cases , officials would be dismissed or punished . Only capital officials of grade 4 and above were exempt from the scrutiny of recorded evaluation , although they were expected to confess any of their faults . There were over 4 @,@ 000 school instructors in county and prefectural schools who were subject to evaluations every nine years . The Chief Instructor on the prefectural level was classified as equal to a second @-@ grade county graduate . The Supervisorate of Imperial Instruction oversaw the education of the heir apparent to the throne ; this office was headed by a Grand Supervisor of Instruction , who was ranked as first class of grade three . 
