Paying for the people who know the laws, procedures, and rules and regulations is not counted as a classroom expense. The reality of student enrollment is that students do not march in uniform cohorts through the school system. Within individual schools, grade levels can have disparate needs for teachers, facilities and supplies. Schools may have too many or too few students for their facilities within existing attendance boundaries. New real estate developments may require schools where none exist.
Class sizes can radically influence the number of teachers needed.
Tracking the academic progress of students from primary to intermediate to middle to high school grades requires maintaining a database of student statistics. Properly allocating resources for today and for the foreseeable future requires people trained in data acquisition and analysis, but they are not counted as classroom expenses. Teacher recruitment Schools could just wait for teachers to knock on their door, but many schools would rather compete for the most talented and desirable teachers. Schools may have particular needs that can be met by focusing efforts in certain venues. Prospective teachers need to be evaluated for compliance with state and federal regulations.