As any district can attest, overhauling teacher evaluations represents a huge lift for all involved. The temptation to look for shortcuts is equally huge.

In 2008, Chicago Public Schools decided to pilot a new teacher evaluation system. Researchers Matthew Steinberg and Lauren Sartain used this opportunity to answer the question "Can the process of evaluating the teachers in a school actually improve a school's performance?" 

For the first cohort of schools implementing the evaluation, principals received extensive training and support, with a focus on how to use the rubric and what to look for when observing teachers. Principals held both pre- and post-observation conversations with teachers. Not unlike what DC learned (see here), this group of schools with their well trained principals realized a statistically significant improvement in students' reading scores compared to schools that did not implement the evaluation. 

But the results were not nearly so strong for the second cohort of schools. What changed? This time, Chicago provided only minimal training to principals. Teachers still got evaluated. They still got feedback. But this cohort of schools reported few learning gains--indeed faring no better than schools that did not implement the new evaluation system at all. 

It seems like a simple lesson to learn. A good evaluation system is only as good as the training and support provided to those asked to deliver it.