Economist Rucker Johnson Shows How School Investments Transform Student Outcomes

Between 2010 and 2013, California enacted three ambitious education reforms. The state introduced transitional kindergarten (TK), the first year of a two-year kindergarten program for children with late birthdays; implemented the Local Control Funding Formula (LCFF), which allocated more money to districts with more socioeconomically disadvantaged students; and expanded the California State Preschool Program (CSPP). When Rucker Johnson, the Chancellor’s Professor of Public Policy at the Goldman School of Public Policy at UC Berkeley, learned about these substantial new investments in early childhood education, he believed it was essential to investigate how the reforms impacted student achievement.

“We came to the state to partner with them and said, ‘If you’re putting that much money into an investment of this magnitude, where’s the evaluation?’” said Johnson, speaking at Yale SOM on April 13 at the second annual Broad Seminar. “‘Let’s link the data to outcomes so we can know what’s working.’”

In an event open to the entire Yale community, Johnson discussed the research he conducted using data provided by the state of California to track the first cohorts of students to benefit from these reforms and measure how third- and fourth-grade outcomes for those students differed from those of previous cohorts. (Johnson’s research has been supported by Austin Land, a postdoctoral fellow at the University of California, Berkeley.)

Launched in 2025, the seminar is a joint initiative of the SOM’s Dean’s Office and The Broad Center at Yale SOM, which fosters the ideas, collaboration, and leadership to help all students—particularly those from underserved communities—to learn and thrive. The Broad Center supports leaders in large, urban public school systems through its signature leadership development programs, the Master’s in Public Education Management and the Fellowship in Public Education Leadership. The 2026 seminar took place during a program week of the Fellowship and the 17 leaders in the current cohort joined the seminar.

While investments in preschool programs alone do not always yield lasting academic results, Johnson found that when combined with other funding increases, the introduction of an additional year of kindergarten produced remarkable learning gains that persisted throughout elementary school. Among socioeconomically disadvantaged children, TK attendance accelerated learning gains in reading and math by an average of six months by third grade, relative to typical students from the same school and cohort who did not attend TK. Those gains were consistently larger in schools with higher levels of per-child funding through the LCFF.

Johnson also analyzed which specific district-level investments amplified learning gains, finding that efforts to increase teacher salaries, shrink class sizes, and mitigate teacher turnover were most effective. Johnson shared statistics demonstrating that the median annual wages in early education for TK teachers are as high as $90,000, whereas teachers in early childhood education settings outside of K-12 schools were paid median wages in the range of $52,000 to $65,000.

The Broad Seminar aims to connect leading education scholars with students, faculty, and public school leaders in the Yale community. After giving his talk, Johnson met with The Broad Fellowship cohort and individually with several faculty members and doctoral students. During his visit, he also attended the Yale economics department’s Labor/Public Economics Workshop.

“You could literally feel the energy in the room,” said Natasha Trivers, assistant dean and executive director of The Broad Center, after the seminar. “Senior public education leaders, faculty, and MBA students were buzzing about the implications of this research and how replicating this kind of methodology could help distill which policy or funding shifts are critical to improving academic outcomes in a school system.”

Attendees at the seminar asked Johnson how he accounted for a high level of variability in the methods used by individual districts to implement reforms. Tommy Welch, regional school superintendent for Boston Public Schools and a current Broad Fellow, who was a principal in California during the period Johnson studied, described his own experience navigating questions about how to allocate new resources. By the end of the talk, fellows and faculty members were speculating on further avenues of inquiry, such as how uncertainty about continued funding affects local decision-making.

Summing up his findings, Johnson noted that collaboration among scholars and practitioners is essential to research like his. “As researchers, we’re trying to evaluate and replicate success,” he said. “That requires connections to local leaders who are actually doing the work—and that’s what Broad and the School of Management are doing.”