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Many people might think the main benefit of a high-quality preschool program is the academic boost it gives young children when they enter elementary school.

But the strongest positive effects may show up years, and even decades, later and have little to do with test scores and grades.

Researchers at Georgetown University have been studying the impact of Tulsa, Oklahoma’s program for two decades.

In a new set of working papers, the researchers found long-term positive outcomes for children who were enrolled in preschool in 2005: Compared to their peers, the children who attended preschool were more likely to take advanced courses and graduate high school on time, more likely to enroll in a higher education program and more likely to vote in elections after turning 18. Most of the new findings have not yet been officially published or peer reviewed.

While the working papers focused on children who are now in their early 20s, additional research from Georgetown is tracking a group of Tulsa children who finished third grade last school year. Researchers found that the third graders who had attended preschool had stronger self-regulation skills and performed better in math.

About 71 percent of Oklahoma’s 4-year-olds, and about 61 percent of 4-year-olds in the Tulsa region, were enrolled in pre-K in 2021.

It’s easy for policy-makers to focus on academic grades, but the study of third graders actually highlights outcomes more important to parents, said Kelly Kane, director of elementary and early childhood education in the school district.

“Test scores aren’t the thing they’re thinking about. They want to ensure that the children are being set up for success in school, they’re being set up for success in life,” Kane said. “Certainly, test scores matter, and we look at that data and we care a lot about that data, but it’s not the only thing that matters.”

When the Georgetown researchers first looked at results from the program years ago, they focused on short-term academic gains, said William Gormley, a co-director of Georgetown’s Center for Research on Children in the United States, which has overseen much of the Tulsa research. But as the preschool students got older, Gormley found that the cognitive gains — such as higher scores on standardized tests — diminished, while social-emotional benefits persisted.

The previous research on Tulsa’s preschool program did show small advantages on math test scores into middle school, but those gains are not as significant as the other benefits, Gormley said.

“As we’ve looked at the data over time, we’ve concluded that the effects on self-regulation in particular, which seems so modest and almost inconspicuous back in 2006, may be a really important piece of the puzzle when you’re trying to figure out why Tulsa’s universal pre-K program is producing such remarkably strong positive effects when children reach young adulthood,” Gormley said.

Related: Why Oklahoma’s public preschools are some of the best in the country

The Tulsa research is part of a larger body of work studying the trajectory of children’s lives after they attend different types of publicly-funded preschool programs. The research also shines a light on the impact preschool can have on students beyond high school.

However, studies of pre-K’s effect on students’ grades have had inconsistent results. A Georgia study, for example, found kids who participated in the peach state’s pre-K showed long-term academic gains in math, while a study of the federally funded Head Start program found that the initial academic advantages children in the program had over their non-participating peers faded out entirely by third grade.

“A lot of specific effects of preschool on standardized tests will diminish over time. But what we’ve seen in Tulsa is that a lot of other remarkably positive developments can be observed along the way,” Gormley said.

“Test scores aren’t the thing [parents are] thinking about. They want to ensure that the children are being set up for success in school, they’re being set up for success in life.”

Kelly Kane, director of elementary and early childhood education, Tulsa public schools

Not all studies of preschool programs have revealed positive benefits. Earlier this year, researchers from Vanderbilt University released their latest findings on Tennessee’s public pre-K program that showed no boosts for children’s grades or behavior from pre-K attendance. Worse, the Tennessee research revealed dismal outcomes for children who participated in the state’s preschool program, which is targeted for children from low-income families. By sixth grade, students who attended a Tennessee preschool performed worse academically, had more behavioral problems and were more likely to be referred to special education services than their peers who had not enrolled.

Dale Farran, a lead author of the Tennessee research, said the findings suggest that preschool needs more focus on play-based learning, as opposed to whole-group instruction and other classroom management tools used with older children.

“[We] have let ourselves get into the idea that what these children need is a lot more academic instruction.” Farran said in an interview with The Hechinger Report in January. “And I would say, no, it’s just the opposite. What you would like to give poor children is a feeling of being cared for and being successful.”

But it’s hard to pinpoint exactly what went wrong in Tennessee: There could be a number of factors influencing the poor results, said Steven Barnett, director of the National Institute for Early Education Research.

“People underestimate the difficulty of getting this right and how many ways it can go wrong,” Barnett said. He has asked Tennessee officials to look at internal data to see whether more recent cohorts of preschool students are faring better.

State officials said the program is now of higher quality than it was at the time the Vanderbilt researchers conducted their study, and the state also spends more money on it than when the students involved in the study attended preschool.

Related: Who should pay for preschool for the middle class?

Researchers have long searched for answers to explain why some preschool programs lead to positive outcomes when others do not.

One major difference between the Oklahoma and Tennessee programs is access — Oklahoma’s preschool program is universal and open to all students, while Tennessee’s is targeted toward low-income families. Some evidence suggests that high-quality preschool programs that are open to all children provide stronger positive benefits to children than targeted programs, possibly because universal programs attract better teachers or offer all children some of the benefits that come from attending school with higher-income peers.

According to NIEER, Tennessee’s program typically enrolls around a fifth of the state’s 4-year-olds. In contrast, about 71 percent of Oklahoma’s 4-year-olds, and about 61 percent of 4-year-olds in the Tulsa region, were enrolled in pre-K in 2021. Those percentages reflect a small dip from previous years that might be due to the coronavirus pandemic, according to ImpactTulsa, which collects the data.

Oklahoma also has had more time to get it right: The state was the second in the nation to create a universal preschool when it launched the program in 1998. From the beginning, Oklahoma has had some quality measures in place, Gormley said: Teachers are required to have a bachelor’s degree, class sizes are limited to 10 students per staff member and programs are funded through the public schools, which means preschool teachers are paid on the same salary scale and have to meet the same standards as teachers at elementary schools in the district. In the 20 years that NIEER has published its annual preschool ratings list, Oklahoma has consistently ranked among the top in the nation for access to its program.

“The scaffolding for universal pre-K in Oklahoma is very promising, but it takes a lot of hard work, a lot of patience, a lot of creative thinking and a lot of critical thinking by lots of program administrators and school administrators and teachers to pull it off,” Gormley said. “They have pulled it off brilliantly in Tulsa.”

Tulsa is not the only program to show promising long-term results beyond test scores for students. A decades-long study of children from the time they attended Perry Preschool in Michigan until they reached age 40 found they were more likely to have graduated high school, have higher earnings and have committed fewer crimes. A study out of Boston published last year found students who attended the city’s public preschool program had fewer disciplinary problems and were more likely to take the SAT, graduate from high school and enroll in college. Students who participated in New Jersey’s pre-K program were less likely to be held back or referred to special education services.

The answer to replicating those programs, Barnett said, is spending money to do what they did.

“Whatever you do, you ought to be spending money to collect data. Are kids getting the experiences you want them to get and are they continuing to benefit from that as they move out of pre-K into K and beyond? And if not, then what do we need to change?” Barnett asked. “It’s not complicated, in that sense. It’s just people don’t want to do these things because they’re not cheap.”

This story about high-quality pre-K was produced by The Hechinger Report, a nonprofit, independent news organization focused on inequality and innovation in education. Sign up for the Hechinger newsletter.

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