Having spent a number of years as a student and a bunch more years as a teacher, I think evaluating teachers from a distance is difficult. Even leaving aside that any and all objective measurements will eventually be gamed, students vary an awful lot and there are many, different ways to be effective (and ineffective).
But if we think good teaching is important, how then should we evaluate teachers? Fred Hiatt in the Washington Post proposes that we do it the same way we do it for lots of other hard-to-evaluate goods and services: let consumers choose:
Should performance be averaged over two or three years? How do you measure the impact of teachers in subjects that aren’t tested, such as art or music? Is it fair to compare a teacher ably supported by a guidance counselor, principal and reading specialist to those teachers left to fend for themselves? . . .
But there’s a way to sidestep those problems, too, or at least take them out of the hands of unwieldy bureaucracies: Just leave it to the school.
Under this model, parents would be given comparable information about a host of available schools. They could send their children to schools that are succeeding and avoid those that are failing. School leaders would be free to hire, evaluate and reward staff as they thought best, with no bureaucratic interference. But if they failed to develop and retain talented teachers, they also would fail to attract enough students, and their schools would go out of business.
This model exists. It’s called charter schools.
Of course, that requires the consent of the political system which, unfortunately, often resists: "Kids' charter crush hits record high".
[New York] City parents desperate to give their children the best education available are storming the doors of charter schools — but nearly 53,000 heartbroken kids will be left out in the cold.