Value-Added Evaluation Hurts Teaching

Joanna Cannon, executive director of the New York City Department of Education's Office of Research and Data, speaks to reporters about the release of individual performance rankings of 18,000 public school teachers while New York City Schools Chancellor Dennis Walcott looks on at the Tweed Courthouse in New York City on Feb. 24.

—Joshua Bright

Here’s the hype: New York City’s “worst teacher” was recentlysingled out and so labeled by the New York Post after the city’s education department released value-added test-score ratings to the media for thousands of city teachers, identifying each by name.

The tabloid treatment didn’t stop there. Reporters chased down teacher Pascale Mauclair, the subject of the “worst teacher” slam, bombarding her with questions about her lack of skill and commitment. They even went to her father’s home and told him his daughter was among the worst teachers in the city.

Now the facts: Mauclair is an experienced and much-admired English-as-a-second-language teacher. She works with new immigrant students who do not yet speak English at one of the city’s strongest elementary schools. Her school, PS 11, received an A from the city’s rating system and is led by one of the city’s most respected principals, Anna Efkarpides, who declares Mauclair an excellent teacher. She adds: “I would put my own children in her class.”

Most troubling is that the city released the scores while warning that huge margins of error surround the ratings: more than 30 percentile points in math and more than 50 percentile points in English language arts. Soon these scores will be used in a newly negotiated evaluation system that, as it is designed, will identify most teachers in New York state as less than effective.

Is this what we want to achieve with teacher-evaluation reform?

Everyone agrees that teacher evaluation in the United States needs an overhaul. Although successful systems exist, most districts are not using approaches that help teachers improve or remove those who cannot improve in a timely way. Clearly, we need a change.

As student learning is the primary goal of teaching, it seems like common sense to evaluate teachers based on how much their students gain on state standardized tests. Indeed, many states have adopted this idea in response to federal incentives tied to much-needed funding.

However, previous experience is not promising. Recently evaluated experiments in Tennessee and New York did not improve achievement when teachers were evaluated and rewarded based on student test scores. In the District of Columbia, contrary to expectations, reading scores on national tests dropped and achievement gaps grew after a new test-based teacher-evaluation system was installed. In Portugal, a study of test-based merit pay attributed score declines to the negative effects of teacher competition, leading to less collaboration and sharing of knowledge.

I was once bullish on the idea of using “value-added methods” for assessing teacher effectiveness. I have since realized that these measures, while valuable for large-scale studies, are seriously flawed for evaluating individual teachers, and that rigorous, ongoing assessment by teaching experts serves everyone better. Indeed, reviews by theNational Research Council, the RAND Corp., and the Educational Testing Servicehave all concluded that value-added estimates of teacher effectiveness should not be used to make high-stakes decisions about teachers.

Why?

First, test-score gains—even using very fancy value-added models—reflect much ...

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