Is it possible to measure teacher effectiveness? For decades, public school principals have subjected teachers to a battery of observations and evaluations purportedly designed to assess the quality of classroom instruction. Rather than yield appreciable information, however, these kinds of teacher assessments merely served as one of the few formal requirements needed to attain lifetime job security, also known as tenure.
On the other hand, the “value-added” method of teacher evaluation continues to show promise as an objective and reliable assessment of teacher quality. Value-added analysis uses standardized tests to estimate teacher effectiveness. This powerful evaluation method employs advanced statistical techniques to project the future performance of individual students based on their past performance. The difference between the projected and actual performance of students determines the value added or subtracted by the teacher.
Value-added analysis has upended the conventional wisdom on teacher quality. For years, public school advocacy groups complained that the most talented teachers snub minority and low-income schools by migrating to less challenging and higher paying schools in culturally and economically homogeneous suburbs.