The two purposes of teacher evaluations are development and quality measurement, as of 2015. Schools rate teachers because they want the most effective and skilled educators in the classroom. Educational professionals design systems that measure teacher quality differently than those that encourage teacher improvement.
Teacher evaluations have failed to adequately distinguish between effective and ineffective teachers, so state education departments and school districts are working to change the way a teacher's quality is measured. Over 3,000 educators who were asked about the purpose of evaluations believe that ratings should measure a teacher's quality performance, but should emphasize development even more.
A teacher evaluation system that helps teachers improve is comprehensive and specific, incorporates a developmental rubric and reinforces desired performance. Student achievement relies on several instructional elements, so a developmental evaluation must include them all. Specific techniques, such as providing goals, monitoring progress and rewarding success, should be included in a developmental evaluation. A rating system that helps teachers improve includes a scale with five scores that indicate whether teachers are lacking a particular skill or whether they are proficient with it. Evaluation methods that develop instructional excellence reward teachers who improve over the course of a school year by setting initial goals in certain areas, and then measuring how successfully teachers achieve them.