The Impact of Experienced Kindergarten Teachers

In the late 1980s, around the same time that the Raging Rooks were learning chess in Harlem, the state of Tennessee launched a bold experiment. At 79 schools – many of which were low income – they randomly assigned over 11,000 students to different classrooms in kindergarten through third grade. The original goal was to test whether smaller classes were better for learning. But an economist named Raj Chetty realized that since both students and teachers were randomly assigned to classrooms, he could go back to the data to analyze whether other features of classrooms made a difference.

Chetty is one of the world’s most influential economists. He’s the winner of a MacArthur genius grant. And his research suggests that excellence depends less on our natural talents than we might expect.

The Tennessee experiment contained a startling result. Chetty was able to predict the success that students achieved as adults imply by looking at who taught their kindergarten class. By age 25, students who happened to have had more experienced kindergarten teachers were earning significantly more money than their peers.

Chetty and his colleague calculated that moving from an inexperienced kindergarten teacher to an experienced one would add over $1,000 to each students annual income in their twenties. For a class of 20 students, an above-average kindergarten teacher could be worth an additional lifetime income of $320,000.

(See extended footnote below.)

Kindergarten matters in many ways, but I never would have expected teachers to leave such a visible mark on their students’ salaries two decades later. Most adults hardly even remember being five years old. Why did kindergarten teachers end up casting such a long shadow?

The intuitive answer is that effective teachers help students develop cognitive skills. Early education builds a solid foundation for understanding numbers and words. Sure enough, students with more experienced teachers scored higher on math and reading tests at the end of kindergarten. But over the next few years, their peers caught up.

To figure out what students were carrying with them from kindergarten into adulthood, Chetty’s team turned to another possible explanation. In fourth and eighth grade, the students were rated by their teachers on some other qualities. Here’s a sample:

Proactive: How often did they take initiative to ask questions, volunteer answers, seek information from books, and engage the teacher to learn outside class?
Prosocial: How well did they get along and collaborate with peers?
Disciplined: How effectively did they pay attention and resist the impulse to disrupt the class?
Determined: How consistently did they take on challenging problems, do more than the assigned work, and persist in the face of obstacles?

When students were taught by more experienced kindergarten teachers, their fourth-grade teachers rated them higher on all four of these attributes. So did their eighth-grade teachers. The capacities to be proactive, prosocial, disciplined, and determined stayed with students longer – and ultimately proved more powerful – than early math and reading skills. When Chetty and his colleagues predicted adult income from fourth-grade scores, the ratings on these behaviors mattered 2.4 times as much as math and reading performance on standardized tests.

Think about how surprising that is. If you want to forecast the earning potential of fourth graders, you should pay less attention to their objective math and verbal scores than to their teachers’ subjective views of their behavior patterns. And although many people see those behaviors as innate, they were taught in kindergarten. Regardless of where students started, there was something about learning these behaviors that set students up for success decades later.

This passage was included in the text as a footnote:

For their next study, with over a million children, Chetty and his colleagues found that more experienced teachers added more value, as measured by gains in their students’ test scores over the year. Students who had effective teachers between third and eighth grade were more likely to go to college, earned high salaries, and saved more for retirement. When an effective teacher left their school, the students in that grade the following year suffered: their odds of attending college dropped. Teacher quality was especially important for the future success of women, in part because they reduced the odds of teenage pregnancy. Replacing a teacher in the bottom 5 percent of student gains with an average one would increase the undiscounted lifetime earnings of a classroom by $1.4 million. If you ever need proof that teachers are underpaid, that number might do the trick.