Consider the Evidence


Sep 11, 2012

Chicago teachers on strike

Chicago teachers on strike

photo by br5ad/

This commentary originally appeared in Chicago Tribune on September 11, 2012.

The Chicago Teachers Union strike erupted over classic issues: an extended day, a new evaluation system and hiring and firing. The union seeks pay raises tied to advanced degrees and years of service rather than merit. Yet, somewhat classically, neither the union nor Chicago Public Schools has put forth research evidence to support their stance.

Research could be helpful in untangling the dispute. Compelling evidence exists to indicate that extending academic learning time, especially for poorly performing students, results in improved student achievement. Research also suggests that to improve the quality of instruction, personnel decisions should consider evidence of teaching effectiveness — rather than relying exclusively on teachers' characteristics such as their academic degrees and how long they've taught.

Researchers have learned that it is not just the amount of instructional time that matters but how that time is used. More instructional time, when combined with quality instruction and the engagement of students (a combination known as academic learning time), has consistently been shown to be predictive of greater student achievement.

Further, RAND Corp. research has shown that students with lower initial student achievement learn at slower rates, and these students, in particular, benefit from more learning time. Thus, one of the best ways to increase student learning is to simultaneously increase the time spent on learning and the quality of instruction. Indeed, extending the school day was a good first step to try to raise student achievement levels.

The second step, improving instructional quality, is more difficult to achieve. Until recently, it was measured by teacher characteristics endorsed by the union (teaching experience, having advanced degrees). Research has shown that a teacher's level of experience matters in the first three to five years, where each year of additional experience helps improve student learning on standardized tests. However, beyond five years, with exceptions for mathematics, additional years of experience do not consistently contribute to improved student learning.

Even the attainment of advanced degrees, which should signal something about teachers' level of preparation for the job, is a poor indicator of teaching quality. Most research studies have found either no relationship between advanced degrees and student achievement or a marginally positive one (again in mathematics). An agreement between CPS and the CTU to hire teachers or determine pay on the basis of past employment in the district, seniority or advanced degrees is unlikely to result in improvements in teaching quality.

Obtaining reliable and valid evidence of teaching effectiveness is possible under Illinois' Performance Evaluation Reform Act, which is being implemented this year. PERA requires CPS and CTU to work together to implement a new evaluation system that will not give school principals free rein to fire teachers, but require an assessment of teachers' professional skills via observation and a measure of student growth.

A Bill and Melinda Gates Foundation study, Measures of Effective Teaching, demonstrates that classroom observations of teaching, when performed by trained professionals not connected to the school, can identify quality teaching associated with high student academic achievement.

A teacher's past record of value-added scores (currently the most widely used measure of student growth) is among the strongest predictors of teaching effectiveness: Teachers who lead students to achievement gains in one year or in one class tend to do so again in other years and classes.

Any agreement reached between CPS and the CTU concerning future personnel decisions should focus on how best to use this more reliable evidence of teaching quality. It would be an important way to demonstrate both sides' professed goal of improving education in Chicago.

Darleen Opfer is director of RAND Education, a division of the nonprofit, nonpartisan RAND Corp.

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