The Office for Civil Rights' new data collection shows vast disparities in regard to teachers.  Racial minorities were twice as likely to attend schools where one out of five teachers were brand new.  Racial minorities were also more likely to attend schools with unlicensed teachers.  Race aside, about 800,000 student attended a school where one out of five teachers lacked the required state licence.  

Teacher quality is inherently a difficult thing to measure with blunt qualification metrics, but studies have show that some blunt measures matter.  First, there is a learning curve to teaching.  While quality may flatten after about five years of teaching, teachers do tend to improve during the first five years or so.  Second, while "certified" teacher encompasses a broad range of teachers and teaching quality, uncertified is a relatively narrow group who have yet to demonstrate the basic requirements to enter a classroom.  As a result, studies do show that uncertified teachers have a negative impact on student achievement.

Interestingly, none of these teacher inequalities have anything to do with tenure.  As very rough measures, they tend to show just how wrong-headed the legal challenges to tenure are.  These numbers show that if ever teacher in the country lost tenure tomorrow and we fired everyone of them on Monday, there are not enough certified teachers to fill our nation's classrooms.  Moreover, this problem is most acute in predominantly minority schools.  Tenure may randomly operate as a burden or disincentive to removing some teachers, but it is not a significant cause of low quality teaching.  For a host of other flaws in the challenges to tenure, see here.