The Extreme Difficulty Of Evaluating Teachers

by Conor Friedersdorf

In an excellent post on teacher evaluation, Jim Manzi brings his characterisitic analytic clarity. Since he writes from the perspective of someone outside the realm of partisan debate his arguments are unlike anything you've likely seen – do read the whole post. I'm going to excerpt one part that interests me:

The goal of an employee evaluation system is to help the organization achieve an outcome. For purposes of discussion, let’s assume the goal of a particular school to be “produce well-educated, well-adjusted graduates.” The question to be asked about this school’s evaluation system is not “Is it fair to the teachers?” It is not even “Does it measure real educational advancement?” Ultimately, all we should care about is whether or not the school produces more well-educated, well-adjusted graduates with this evaluation system than if it used the next-best alternative. In this way, it is like a new training program, investment in better physical facilities, or anything else that might consume money or time.

The fairness or accuracy of the measurement versus some abstract standard is the means; changing human behavior in a way that increases overall organizational performance is the end. To put a fine point on it, if a teacher evaluation that is based on a formula that considers only blood type, whether it is raining on the day of the evaluation and the last digit of the teacher’s phone number is the one does the best job producing better educated and adjusted graduates, then that’s the best evaluation system.

That seems exactly right to me. And it helps explain the inherent tension between teachers unions and the rest of us. Unions exist to protect the interests of their members. Even in the best case scenario, that means lobbying for an evaluation system that maximizes fairness to the people being evaluated. As citizens, our primary goal should be creating the best education system possible, even if doing so sometimes means (for example) that the teacher most desserving of a bonus doesn't get one. Saying that there is a conflict between the common good and the ends of teachers unions isn't a condemnation of the latter. It's just a fact. And everyone seems to understand the basic concept if you talk about prison guard unions.

Noah Millman has a post reacting to Manzi, and it too is worth reading.

Evaluations establish the principle that there is such a thing as performance in the first place. A great deal of discussion nowadays in education revolves around the idea that what we need to “fix the schools” is great teachers. But if that’s what we need, we’ll never do it. What we need, instead, are mechanisms for getting marginally better performance, year after year, from a teaching pool that remains merely adequate.

One bit of low-hanging fruit for achieving that goal, meanwhile, is the ability to dismiss the bottom 5% of teachers in terms of performance. Not only are these teachers failing comprehensively in their own classrooms, but their mere presence has a corrosive effect on an entire organization – on the teachers, on the students, on the management of the school. But right now, firing these teachers is essentially impossible. For all the difficulty of doing a rigorous evaluation in order to improve teaching performance across the board, I suspect it is a whole lot easier to identify the worst teachers in the school. If that could be done, the pressure to be able to terminate them would be significant, and that could do a lot to improve school performance right there.

I think most people are able to pick out the very best and very worst teachers in any school they observe closely. More here.