Is a good teacher one who makes students enjoy class the most or one who is strict and has high standards? And are those two types even at odds?

new study that tries to quantify this phenomenon finds that on average, teachers who are good at raising test scores are worse at making kids happy in class.

“Teachers who are skilled at improving students’ math achievement may do so in ways that make students less happy or less engaged in class,” writes University of Maryland’s David Blazar in the study, published in the peer-reviewed journal Education Finance and Policy.

The analysis doesn’t suggest that test scores are a poor measure of teacher quality, but does highlight the different ways teachers may be effective.

The research uses data from four school districts across three states between 2010 and 2013; in one year, students were randomly assigned to fourth- and fifth-grade teachers, allowing researchers to study what effect different teachers had on students. Those students were also surveyed about their behavior, self-efficacy, and happiness in class.

A large body of past research has found that teachers have a meaningful impact on student test scores, and a number of more recent studies have found that teachers also impact other measures — sometimes called non-cognitive outcomes — such as behavior and attendance. 

The latest study asks a few big questions.

First: Do teachers have an impact on students’ attitudes and behavior, as measured by student surveys? Here, the answer is convincingly yes, consistent with the emerging research.

Second: Are the statistical estimates — often called value-added  measures — of teacher impacts on test scores and non-cognitive skills accurate? The study examined this by comparing the statistical estimates to the results from from random assignment, and it found that the answer varies. Value-added measures are quite accurate for predicting test scores — an important finding in light of the charged debate on whether to judge teachers by these metrics. But it concludes that the statistical models are often biased for measuring  impact on student attitudes, suggesting that attempting to evaluate teachers in this regard may be misguided.

Finally: Is a teacher’s performance, measured by test scores, similar to performance according to other measures? This question is especially important because it’s key for understanding how to think about teacher quality and how to evaluate it.

The study concludes there was only a weak relationship between test score performance and student behavior and feeling of efficacy in math. But when it came to student happiness, there was a moderate negative association — on average, greater test score gains meant less happy students.

What explains this potentially surprising inverse relationship?

It could be that teachers who were less demanding were more popular because their instruction was less likely to promote learning — but more enjoyable for students. Maybe those teachers just popped in a video on many days; perhaps they never gave homework.

Blazar, for his part, is skeptical of this theory.

“I’m not sure that’s a likely explanation in large part because teachers’ emotional support for students … seems to be really predictive of how happy students are in class,” he said. “Building an emotionally supportive classroom environment is something that educators and researchers have cared about for a long time.”

Another interpretation, then, is that measures of teacher effectiveness based on test scores leave out important dimensions of what makes a good teacher — such as caring for students, something that might show up in happiness surveys.

Blazar emphasizes that while the correlation was negative and statistically significant it was not strong in size, meaning that there were certainly teachers who succeeded in improving both test scores and happiness.

Past research has generally shown that test-based measures capture some, but not all, of the components of effective teaching. Test score results tend to be only modestly related to other measures of performance, like classroom observations or effects on student attendance.

On the other hand, teachers’ impacts on tests have rarely been negatively related to other measures. In fact, there is usually a small positive association, including with regards to student surveys. Moreover, a number of studies have linked teachers’ and schools’ test score impacts to longer-term results, including adult income and college success.

“[Test score value-added] clearly can’t be all about things we don’t care about, such as test prep, if it translates into longer-run outcomes,” Blazar said.

“I think that both are likely important,” he said, referring to test scores and students’ engagement and happiness in class.

“Hopefully we can get to a place where teachers are good at multiple skills,” Blazar said. “Rather than just documenting this pattern, I would want to use this information to say, if you’re good at raising test scores but not as good at engaging students, how can we get you to a place where you can do both at the same time?”

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