One thing I admire about Bill Gates is that he isn't afraid to update his thinking when presented with new information. I've written in the past about Gates' annual letter on his philanthropic activities, which always includes a section on the nearly $400 million his foundation spends each year on American education reform. In these letters, Gates has been careful to praise teachers while simultaneously advocating for more rigorous, often data-based evaluation in order to weed out low performers. In his 2010 letter, for example, Gates controversially called student testing the model for teacher evaluation, noting: "It is amazing how little feedback teachers get to help them improve, especially when you think about how much feedback their students get. Students regularly have their skills measured with tests. The results show how they compare to other students."
The new 2012 letter, however, marks a significant shift in Gates' thinking, and shows he has learned a lot from dialogue with classroom teachers. The letter argues strongly in favor of teacher peer review, a more holistic, classroom-observation based evaluation strategy that is popular with teachers and their unions. Gates praises a program in Tampa in which teachers receive feedback from both their principal and a team of trained peer evaluators. "Most teachers want more feedback and will use it to improve, even if the financial rewards for performance are comparatively modest," Gates writes.
Last year I visited the Math and Sciences Leadership Academy, a Denver public elementary school built around teacher peer review. I was really impressed, and you can read about the school here. To learn more about classroom observation as a teacher evaluation strategy, see this wonderful paper by my colleagues at the New America Foundation, which shows detailed rubrics on what effective teacher coaches and evaluators should look for when they step into a classroom.