As everyone in the education world already knows, several news media organizations won a lawsuit that forced the New York City Department of Education to release many of the teacher-level value-added scores it has been collecting as part of its accountability system. The result? The public unveiling of confusing, unreliable, and—apparently—error-riddled data.

Before we go further down the teacher evaluation path, now is a good time for education reformers to pause and ask themselves whether this kind of top down effort is really what will lead our schools to excellence?

The question is not whether student achievement data should be used as one of several measures of teacher effectiveness, but rather how those data should be used and who is ultimately in the driver’s seat.

Critics of using test data argue that it’s unfair; that standardized tests are imperfect and therefore cannot be used to determine whether students have learned what they should have, and certainly not whether teachers have taught what they were supposed to.

Teachers ultimately should be held accountable for how well they are able to drive achievement in their classrooms.

Such arguments are misguided for lots of reasons, chief among them that there is, in no profession, a perfect measure of effectiveness. And teachers ultimately should be held accountable for how well they are able to drive achievement in their classrooms.

But these critics are correct on a larger point: no matter how well developed the tool, it needs to be reality checked. Of course, the one thing critics—teacher unions foremost among them—hate more than giving Departments of Education the power to determine who should be hired, fired, or promoted is letting principals make those decisions. As just one example, in a 2010 New York Times “Room for Debate” article, Richard Kahlenberg of the Century Foundation explained Albert Shanker’s opposition to allowing principals to make firing decisions:

Who should make the decision about which teachers are fired? Not the principals, Shanker argued. They might play favorites and fire excellent teachers with whom they personally clashed. Besides, how would a principal trained in physical education or history know what makes an excellent French teacher?

But, in order to dramatically improve student performance, we simply must create a system where teachers are free to teach and leaders are obligated to lead. To that end, it’s time for education reformers to get out of the business of trying to improve the civil service rules of our broken education bureaucracies and get back into the business of empowering educators—including school leaders—to get results for kids.

Test score results, while imperfect, are useful data points. But it’s up to the principals to use those results—or not—to make school-level staffing decisions. Because, in the end, it’s the school leader who needs to determine who are the most and least effective teachers in his/her school, and it’s the leader who needs to work with teachers and the school community to drive student learning. By creating a system that, by labeling teachers for them, essentially tells principals which teachers should be kept and which should go, we are absolving principals of responsibility for evaluating their own teachers. And we’re allowing them to escape responsibility for the role they play in ensuring school-level student achievement and growth.

The accountability formula should be pretty simple: hold principals accountable for the results of their schools. Give them the tools (including access to teacher-level achievement data), resources, and autonomy they need to make staffing decisions and to set the school culture. In other words: we need to stop trying to bypass principals in our effort to foster high classroom-level achievement; we need to stop trying to principal-proof our schools.

A version of this post originally appeared on the Common Core Watch blog.

Kathleen is the Superintendent and Chief Academic Officer at the Partnership for Inner-City education and a Senior Visiting Fellow at the Thomas B. Fordham Institute. Before joining the Partnership, Kathleen served as the Senior Advisor for Policy and Instruction at the College Board, as the Director of Curriculum and Professional Development at Achievement First, and the Director of Teacher and Principal Professional…

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