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New York Gov. Andrew M. Cuomo’s proposal for overhauling how teachers are evaluated, compensated, and protected from losing their jobs appears to be meeting stiff resistance from the state legislature, which may create a special commission as a next step. The most controversial element of Cuomo’s plan would tie 50 percent of reading and math teachers’ evaluations to their students’ standardized test scores.

If the ultimate goal is to improve the quality of teaching, depending so much on highly unreliable scores is likely to be counterproductive. A much more effective and proven approach is to promote team-based, data-driven support systems to help teachers become better at their jobs, day in and day out...