OF all the goals of the education reform movement, none is more elusive than developing an objective method to assess teachers. Studies show that over time, test scores do not provide a consistent means of separating good from bad instructors.
Test scores are an inadequate proxy for quality because too many factors outside of the teachers’ control can influence student performance from year to year — or even from classroom to classroom during the same year. Often, more than half of those teachers identified as the poorest performers one year will be judged average or above average the next, and the results are almost as bad for teachers with multiple classes during the same year.
Fortunately, there’s a far more direct approach: measuring the amount of time a teacher spends delivering relevant instruction — in other words, how much teaching a teacher actually gets done in a school day.
Read the full article here: A New Measure for Classroom Quality – NYTimes.com.