This comprehensive report neatly summarizes what we know about teacher effectiveness, turnover, distribution, and tenure--and their relation to the overrepresentation of low quality teachers in high poverty schools. Miller and Chait start off by examining the concept of teacher quality, arguing that traditional qualifications and licensure matter far less than value-added measures and experience. While allowing that value-added measures aren't perfect, they note that these are "at least as good as subjective ratings made by principals, at least where the very most effective and very least effective teachers are concerned." A noteworthy point, considering that it's often this same principal subjectivity that tenure advocates cite as justifying tenure in the first place. Next up is teacher turnover. Miller and Chait build the case that not only are high-quality teachers distributed unevenly thanks to poor working conditions, HR practices, and personal preferences, but that teacher turnover patterns exacerbate the disparity. "Effectiveness breeds contentment," they say, i.e. effective teachers are more likely to stay put. But high-poverty schools often have fewer effective teachers to begin with, and the good ones often leave quickly for better schools or other lines of work. Why? In this realm, opposites do not attract. Good teachers want to work alongside other good teachers, and teachers generally seek schools where they share "an ethnic or cultural affinity." Thus, "a vicious cycle" is born wherein bad schools attract fewer effective teachers and then lose them to better schools, making it ever harder to attract the next crop of talent. Ineffective teachers, meanwhile, are passed around like hot potatoes by bad schools, since tenure makes it difficult to fire them. The authors don't engage in an all-out attack on tenure but do urge policymakers to reexamine present policies. "The role that tenure policies play in preserving a skewed distribution of teacher quality cannot be ignored," they conclude. Indeed. The full report is here.
