I pay a lot of attention to teacher evaluation in this country, and it seems that the issue grows in urgency every day. Yet I have to stop and ask: How much can we expect teacher evaluation to accomplish?

There's no one I respect more as an authority on the teaching profession than Linda Darling-Hammond, so it was with great interest that I saw this brief for policymakers on WaPo's Answer Sheet blog. The brief, titled "Getting Teacher Evaluation Right," was created in collaboration with Jesse Rothstein and other experts. It's a great take on value-added and other salient issues—I wish it'd been published before RttT—but it leads me to wonder whether our expectations for evaluation systems are still too high.

Having zero bad teachers would do wonders for the profession and for our students, but we're far from agreement on the best way to create such a reality. Ensuring that all teachers gain expertise and improve over time is also important, but difficult to ensure at scale. Darling-Hammond's focus is on professional growth, but I think most of the current public interest in teacher evaluation is focused on firing poor teachers. Both evaluative functions have a role in improving the performance of schools, but just how big are these roles?

I agree with Darling-Hammond that teacher evaluation is very important, and that we should do everything we can to ensure that our systems and processes for it are absolutely top-notch.

But I don't think it's a silver bullet. The vast majority of teachers don't need to be fired, and don't need to rely on the formal evaluation process to grow as professionals.

While it's foolish to not have effective evaluation systems, creating such systems is not a panacea. In other words, good evaluation systems are necessary but not sufficient. They won't overcome the effects of poverty, underfunding, inadequate compensation, or poor working conditions. Darling-Hammond's brief concludes:

With these features in place, evaluation can become a more useful part of a productive human capital system, supporting accurate information about teachers, helpful feedback, and well-grounded personnel decisions. Getting Teacher Evaluation Right (Answer Sheet, Washington Post)

She does not say that better evaluation systems will close persistent achievement gaps or launch the US to the front of the pack internationally.

I would be very interested to learn of any other sector that has achieved substantial performance gains by reforming its evaluation processes. We're putting a lot of eggs in the "improve teacher evaluation to improve student learning" basket, but no one even seems to be asking whether this strategy has any merit.