The Brookings Institute takes a balanced look at value-added teacher evaluations, which uses student academic growth to measure teacher effectiveness. The authors conclude that our current forms of evaluations, in which no more than 1% of teachers are rated unsatisfactory, “failed to differentiate meaningfully among levels of teaching effectiveness.” Value-added, which incorporates student longitudinal test data (how a student improves over time), is imperfect but necessary:

Critics of value-added methods have raised concerns about the statistical validity, reliability, and corruptibility of value-added measures. We believe the correct response to these concerns is to improve value-added measures continually and to use them wisely, not to discard or ignore the data.

Here’s the full report. The take-away is that value-added teacher evaluations shouldn’t be used solely to determine hiring, firing, tenure, compensation, etc. But, explain the authors, this information on student growth “surely…ought to be in the mix given the empirical evidence that it predicts more about what students will learn from the teachers to which they are assigned than any other source of information.”