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The Full Measure of a Teacher

The Full Measure of a Teacher


When students look back on their most important teachers, the social aspects of their education are often what they recall. Learning to set goals, take risks and responsibility, or simply believe in oneself are often fodder for fond thanks—alongside mastering pre-calculus, becoming a critical reader, or remembering the capital of Turkmenistan.

It’s a dynamic mix, one that captures the broad charge of a teacher: to teach students the skills they’ll need to be productive adults. But what, exactly, are these skills? And how can we determine which teachers are most effective in building them?

Test scores are often the best available measure of student progress, but they do not capture every skill needed in adulthood. A growing research base shows that non-cognitive (or socio-emotional) skills like adaptability, motivation, and self-restraint are key determinants of adult outcomes. Therefore, if we want to identify good teachers, we ought to look at how teachers affect their students’ development across a range of skills—both academic and non-cognitive.

A robust data set on 9th-grade students in North Carolina allows me to do just that. First, I create a measure of non-cognitive skills based on students’ behavior in high school, such as suspensions and on-time grade progression. I then calculate effectiveness ratings based on teachers’ impacts on both test scores and non-cognitive skills and look for connections between the two. Finally, I explore the extent to which measuring teacher impacts on behavior allows us to better identify those truly excellent educators who have long-lasting effects on their students.

I find that, while teachers have notable effects on both test scores and non-cognitive skills, their impact on non-cognitive skills is 10 times more predictive of students’ longer-term success in high school than their impact on test scores. We cannot identify the teachers who matter most by using test-score impacts alone, because many teachers who raise test scores do not improve non-cognitive skills, and vice versa.

These results provide hard evidence that measuring teachers’ impact through their students’ test scores captures only a fraction of their overall effect on student success. To fully assess teacher performance, policymakers should consider measures of a broad range of student skills, classroom observations, and responsiveness to feedback alongside effectiveness ratings based on test scores.

A Broad Notion of Teacher Effectiveness

Individual teacher effectiveness has become a major focus of school-improvement efforts over the last decade, driven in part by research showing that teachers who boost students’ test scores also affect their success as adults, including being more likely to go to college, have a job, and save for retirement (see “Great Teaching,” research, Summer 2012). Economists and policymakers have used students’ standardized test scores to develop measures of teacher performance, chiefly through a formula called value-added. Value-added models calculate individual teachers’ impacts on student learning by charting student progress against what they would ordinarily be expected to achieve, controlling for a host of factors. Teachers whose students consistently beat those odds are considered to have high value-added, while those whose students consistently don’t do as well as expected have low value-added.

At the same time, policymakers and educators are focused on the importance of student skills not captured by standardized tests, such as perseverance and collaborating with others, for longer-term adult outcomes. The 2015 federal Every Student Succeeds Act allows states to consider how well schools do at helping students create “learning mindsets,” or the non-cognitive skills and habits that are associated with positive outcomes in adulthood. In one major experiment in California, for example, a group of large districts is tracking progress in students’ non-cognitive skills as part of their reform efforts.

Is it possible to combine these two ideas by determining which individual teachers are most effective at helping students develop non-cognitive skills?

To examine this question, I look to North Carolina, which collects data on test scores and a range of student behavior. I use data on all public-school 9th-grade students between 2005 and 2012, including demographics, transcript data, test scores in grades 7 through 9, and codes linking scores to the teacher who administered the test. The data cover about 574,000 students in 872 high schools. I focus on the 93 percent of 9th-grade students who took classes in which teachers will also have traditional test score-based value-added ratings: English I and one of three math classes (algebra I, geometry, or algebra II).

I use these data to explore three major questions. First, how predictive is student behavior in 9th grade of later success in high school, compared to student test scores? Second, are teachers who are better at raising test scores also better at improving student behavior? And finally, what measure of teacher performance is more predictive of students’ long-term success: impacts on test scores, or impacts on non-cognitive skills?

The Predictive Power of Student Behavior

To explore the first question, I create a measure of students’ non-cognitive skills by using the information on their behavior available in the 9th-grade data, including the number of absences and suspensions, grade point average, and on-time progression to 10th grade. I refer to this weighted average as the “behavior index.” The basic logic of this approach is as follows: in the same way that one infers that a student who scores higher on tests likely has higher cognitive skills than a student who does not, one can infer that a student who acts out, skips class, and fails to hand in homework likely has lower non-cognitive skills than a student who does not. I also create a test-score index that is the average of 9th-grade math and English scores.

I then look at how both test scores and the behavior index are related to various measures of high-school success, using administrative data that follow students’ trajectories over time. The outcomes I consider include graduating high school on time, grade-point average at graduation, taking the SAT, and reported intentions to enroll in a four-year college. Roughly 82 percent of students graduated, 4 percent are recorded as having dropped out, and the rest either moved out of state or remained in school beyond their expected graduation year. Because I am interested in how changes in these skill measures predict long-run outcomes, I control for the student’s test scores and behavior in 8th grade. In addition, my analysis adjusts for differences in parental education, gender, and race/ethnicity.

My first set of results shows that a student’s behavior index is a much stronger predictor of future success than her test scores. Figure 1 plots the extent to which increasing test scores and the behavior index by one standard deviation, equivalent to moving a student’s score from the median to the 85th percentile on each measure, predicts improvements in various outcomes. A student whose 9th-grade behavior index is at the 85th percentile is a sizable 15.8 percentage points more likely to graduate from high school on time than a student with a median behavior index score. I find a weaker relationship with test scores: a student at the 85th percentile is only 1.9 percentage points more likely to graduate from high school than a student whose score is at the median. The behavior index is also a better predictor than 9th-grade test scores of high-school GPA and the likelihood that a student takes the SAT and plans to attend college.