Popular modes of evaluating teachers are fraught with inaccuracies

In conclusion
New approaches to teacher evaluation should take advantage of research on teacher effectiveness. While there are considerable challenges in using value-added test scores to evaluate individual teachers directly, using value-added methods in research can help validate measures that are productive for teacher evaluation.

Research indicates that value-added measures of student achievement tied to individual teachers should not be used for high-stakes, individual-level decisions, or comparisons across highly dissimilar schools or student populations. Valid interpretations require aggregate-level data and should ensure that background factors — including overall classroom composition — are as similar as possible across groups being compared. In general, such measures should be used only in a low-stakes fashion when they’re part of an integrated analysis of teachers’ practices.

Standards-based evaluation processes have also been found to be predictive of student learning gains and productive for teacher learning. These include systems like National Board certification and performance assessments for beginning teacher licensing as well as district and school-level instruments based on professional teaching standards. Effective systems have developed an integrated set of measures that show what teachers do and what happens as a result. These measures may include evidence of student work and learning, as well as evidence of teacher practices derived from observations, video- tapes, artifacts, and even student surveys.

These tools are most effective when embedded in systems that support evaluation expertise and well- grounded decisions, by ensuring that evaluators are trained, evaluation and feedback are frequent, mentoring and professional development are available, and processes are in place to support due process and timely decision making by an appropriate body.

With these features in place, evaluation can be- come a more useful part of a productive teaching and learning system, supporting accurate information about teachers, helpful feedback, and well-grounded personnel decisions.

Kappan magazine - Teacher evaluation