The start of another school year also marks another automatic step up the salary scale for most of New York’s 225,000 public school teachers, typically producing a raise of at least 1 to 2 percent in addition to any base pay increase called for by their union contracts. Teachers can also move laterally, to better-paid “lanes” on the salary scale, by earning a master’s degree and additional post-graduate credits.  But a new study by the Manhattan Institute’s Marcus Winters, confirming a wealth of other research, shows that the credentials valued under teacher contracts don’t equate to better teaching.

Winters writes:

In the U.S. public school system today, the method used to determine teacher effectiveness—and thus to drive salary, promotion, and tenure decisions—is based on a few external credentials: certification, advanced degrees, and years of experience in the classroom. Yet according to a new analysis of student performance in Florida that two colleagues and I conducted, little to no relationship exists between these credentials and the gains that a teacher’s students make on standardized math and reading exams. Our expansive study included all test-taking public elementary school students in the state of Florida over a period of four years.

Our study, to be published in the peer-reviewed journal Economics of Education Review, builds on two decades of research from a variety of school systems and confirms a consistent finding: external teacher credentials tell us next to nothing about how well a teacher will perform in the classroom. Such research has not, however, yet had a substantial effect on the practices of U.S. public schools. Today’s public school system continues to rely on external teacher credentials to decide who gets to teach and how much a teacher is paid. Though the debate over how most accurately to use statistical measures to identify teacher quality is far from completed, the general finding that there is a vast difference between the system’s best and worst teachers is no longer in serious dispute. The large body of research on teacher quality suggests that a new method of identifying the best teachers is needed—one that focuses on measuring the contributions that teachers actually make in the classroom.

Weighty statistical analysis aside, most of us would probably say we know a good teacher when we see one. For that matter, pretty much everyone in a typical public school community — starting with principals and parents — knows who the best teachers in the school are. And everyone knows teachers who are no longer trying, or perhaps were not very good teachers to start with.  But teacher tenure laws and rigid contractual pay structures ensure that all teachers with the same experience and credential levels are treated equally, regardless of performance. Indeed, under most contracts in New York today, a lazy, lousy teacher with “Masters plus 30” credits (awarded, in many cases, by the teachers’ union itself) is paid more than a good teacher with a mere M.A.

Whether or not you believe test scores have been oversold as a measure of teacher effectiveness, can’t we all at least agree that it’s unfair, wasteful and counterproductive to (a) provide the vast majority of teachers with lifetime job tenure after just three years on the job, and (b) compensate our most important front-line educational professionals on the basis of seniority and credentials of dubious value, as if they were bolt-tighteners in some post-war auto factory?