Principals are critical to the success of any school improvement effort--from increasing academic rigor toward college- and career-ready standards to teacher evaluation and support. They ensure this success by building a strong, shared vision and leading effective implementation for staff, students, and families. The federal government has an…

In June 2009, The New Teacher Project's study, "The Widget Effect: Our National Failure to Acknowledge and Act on Differences in Teacher Effectiveness", drew national attention to the issue of ineffective teacher evaluation systems. The study documents how teacher evaluation systems ignore variations in performance, giving virtually all…