The study focuses on the tension teachers face between the demand that they hold high expectations for their students and the reality that they face when they confront the evidence at their disposal. The author argues that this tension is not easily avoided; there are good arguments for both optimism and evidentialism. We can recast this tension when we recognize that expectations are noisy signals of more fundamental underlying factors.

High expectations often signal to us that the teacher is committed to doing her job well. It is that commitment that matters to us. A teacher with...