Teacher assessment in DC

This is one that's going to be getting an increasing amount of attention, as the Secretary of Education has said that evaluation of teachers and principals is going to be one of the things he's looking for in his distribution of future federal funds.

Washington D.C. schools Chancellor Michelle Rhee is holding a series of listening sessions with D.C. teachers as she plans to change the system by which they are evaluated. It seems that no one is particularly satisfied with the current system, but Rhee's suggestion, of adding student test scores, among other items, isn't popular, either:

Neither side is happy with the current teacher evaluation system, which involves a series of classroom observations by principals, who often have neither the time nor the expertise in subject matter to render a fair judgment on a teacher's effectiveness. Nevertheless, the system has been used to put at least 150 teachers on the so-called 90-day plan, which places them on notice to improve their performance or face dismissal.

How trustworthy is the value added system?
But even experts who regard a value-added system as an improvement over current evaluation schemes caution that it comes with serious potential pitfalls. One is that the smaller the student sample, the more statistically unreliable the result. In other words, measuring test score growth across a school, or even a grade within a school, is more valid than looking at a single teacher and a class or 15 or 20 students.