A wealth of evidence suggests that attending preK boosts kindergarten readiness, and other benefits can last into adulthood.

In 1965, at the height of President Lyndon Johnson’s campaign to “break the cycle of poverty” in communities across the United States, the federal government piloted an innovative, eight-week summer learning program called Head Start, which aimed to help children from low-income families make a successful transition to elementary school. For more than half a century, the program has endured and evolved. It now serves more than 1 million children and families annually across the entire school year through the Early Head Start program for children from birth to age 3, the Head Start preschool program for 4- and 5- year-olds, and programs for children of migrant workers and American Indian/Alaskan Native children.

Another 1.64 million children are now enrolled in public prekindergarten programs funded by 45 states and the District of Columbia (Institute of Education Sciences, 2021). Some of these state programs (such as California’s) are as old as Head Start, and many others were created in the 1980s and 1990s, but most of the growth in these programs has occurred over the past decade, led by cities as well as states. Further, the push for universal preK has recently gained traction among federal policy makers, with President Joe Biden proposing a $1.8-trillion American Families Plan that would make preK available, beginning at age 4, to every child in the country.

For all of this progress, however, we continue to see wide gaps in access to preK and other early childhood programs. Across the U.S., Latinx (43%), Pacific Islander (39%), and Indigenous children (45%) are less likely to be enrolled in early childhood education than white (50%), Black (53%), or Asian-American children (56%). Among children of parents with a high school diploma or less, only 40% attend early childhood programs, compared with 60% of children whose parents have a bachelor’s degree or higher. Further, most states have far too few seats to accommodate all eligible children, and enrollment rates vary widely from state to state — for instance, fewer than one-third of children in Mississippi are enrolled in a public prekindergarten program, compared to more than 80% of children in Vermont and the District of Columbia (Friedman-Krauss et al., 2021). And, of course, the COVID-19 pandemic has taken a heavy toll on enrollments. In Virginia, for example, preK enrollment fell by nearly 20% between fall 2019 (prepandemic) and fall 2020 (mid-pandemic), and the decrease was 30% among children who qualify for free or reduced-price lunch (Bassok & Shapiro, 2021).

Overall, just under half of the country’s 3- and 4-year-olds were enrolled in center-based care (including private tuition-based programs) in 2019, a far lower proportion than in most European nations (United Nations Children’s Fund, 2019) and one that has remained relatively flat over the past 10 years (Institute of Education Sciences, 2021). Even if we include 5-year-olds in the data (capturing more of our recent growth in preK programs), we lag well behind most other developed nations: Among the 48 countries monitored by the Paris-based Organization for Economic Cooperation and Development (OECD, 2021), the U.S. ranks 42nd in early childhood education enrollment.

The effects of attending preK

Still, the question remains: Does it matter that so many American children are unable to attend a preK program? If cities, states, and the federal government continue to expand access to preK, can we expect this to result in better outcomes for those children? As numerous empirical studies have found, significant disparities in school-related knowledge and skills often emerge in early childhood; by the time kindergarten begins, children from low-income backgrounds tend to have already fallen behind their more affluent peers in key academic domains (Reardon & Portilla, 2016). So, will increased enrollments in preK help close these early gaps, perhaps resulting in fewer achievement gaps in later years?

Given the renewed national interest in universal preK, it’s important to review what we actually know from decades of research into the short- and long-term effects of these programs. A wealth of evidence shows that children who attend preK and other early childhood programs have higher pre-academic skills at kindergarten entry than those who don’t attend, and the academic, social, and personal benefits of attending preK can last long into adolescence and adulthood. For these reasons, I argue, investing in universal public preK should continue to be an urgent policy priority.

Preparation for school

Around the time that the federal government began the Head Start program, several small “demonstration” programs — including the Perry Preschool Project in Michigan and the Abecedarian program in North Carolina — began conducting rigorous research into the effects of attendance in these programs on children’s academic, health-related, socioemotional, and socioeconomic outcomes. (These were so-called “gold standard” studies, comparing two sets of children, one that was randomly selected to attend a preschool and one that was not.) This research, along with studies of the Chicago Child-Parent Center program in the 1980s, generated some of the first solid evidence from the U.S. that early childhood programs can improve children’s school readiness (Schweinhart et al., 2005; Ramey & Campbell, 1984; Weikart, 1978).

The early findings from these programs are often considered “proof of concept,” providing evidence that preK can, in fact, effectively prepare kids for school. However, since neither the programs themselves nor the students they served were typical of preK in general, it has been difficult to say to what extent the results apply to other preschools. For one, these programs were very small, and they included health care services, services for parents, and academic supports that continued when the students were in early elementary school. Further, these programs served children from very low-income families and, in the case of Perry Preschool, all of the students were Black. Today’s public preK programs tend to be much more diverse, both socioeconomically and demographically, and they rarely include these other “wraparound services.”

Over the past few decades, though, researchers have gathered an abundance of evidence showing that children who attend more typical public preK programs also tend to become better prepared for kindergarten. For example, a group of scholars recently synthesized the results of rigorous evaluations of 18 programs, concluding that eight of the studies found evidence that students had significantly increased their language skills by the time they entered kindergarten, 17 studies found increased literacy skills, and 14 found increased math skills (Meloy, Gardner, & Darling-Hammond, 2019). Notably, these program evaluations included both universal programs that are open to all age-eligible children (such as California’s transitional kindergarten program and city-run programs in Boston and Tulsa) and programs that serve only low-income or at-risk children (such as the Abbott Preschool Program in New Jersey).

Lasting benefits

Despite the clear evidence that preK programs improve children’s kindergarten readiness, there is mixed evidence that these benefits translate to higher test scores later on, in elementary school and beyond. Consider Head Start, for example. While some studies have found that the benefits of attending Head Start can last into early elementary school (Deming, 2009), the findings from a large, randomized control trial showed little evidence of benefits continuing through 3rd grade, raising questions about whether Head Start results in any lasting gains for children (Puma et al., 2010).

However, when researchers went back and reanalyzed the data from this large study, they found that the original researchers’ main finding (that Head Start had no lasting benefits on average) masked important variations among specific student groups. For example, students with limited English proficiency showed significant long-term benefits from the program, as did children who were found to have lower cognitive skills when they began Head Start. Also, some Head Start centers were shown to be more effective than others, suggesting that well-run programs may have more lasting effects on student performance (Bloom & Weiland, 2015).

Further, while attending preschool may not always lead to higher test scores later in elementary school, researchers have identified other benefits that do appear to last. For instance, a recent study of North Carolina’s public preK programs revealed that participating students are significantly less likely to be placed in special education in subsequent years (Muschkin, Ladd, & Dodge, 2015).

Among the 48 countries monitored by the OECD, the U.S. ranks 42nd in early childhood education enrollment.

Moreover, long-run follow-up studies of the Perry Preschool Program, Abecedarian, and Chicago Child-Parent Centers suggest that attending preK can result in improved adolescent and adult outcomes many years later. Compared to similar children who were not randomly selected to participate in these programs, children who did attend went on to have more positive life trajectories overall: They scored higher on cognitive measures in adolescence, had fewer special education placements, were less often held back a grade, were more likely to complete high school and attend college, were less likely to have criminal records, and had higher rates of adult employment (Campbell et al., 2012; Reynolds, Ou, & Temple, 2018; Schweinhart et al., 2005).

These sorts of long-term benefits have been found in studies of more recent preK programs, too (though such studies are rare since few programs have been studied rigorously over time). For example, a very recent study of Boston’s public preK program found that participants were more likely to graduate high school and attend a four-year college and less likely to have discipline infractions or juvenile justice interactions (Gray-Lobe, Pathak, & Walters, 2021). Similarly, a synthesis of 22 experimental and quasi-experimental studies from 1960 through 2016 found that, on average, children who attend preK are less likely to be placed in special education, less likely to be retained a grade, and more likely to graduate from high school (McCoy et al., 2017).

New frontiers in the research

As I’ve described, a wealth of empirical evidence shows that children who attend preK tend to have higher scores on school readiness measures, and a growing body of evidence suggests also that the benefits of these programs can last long into adolescence and adulthood. Researchers remain puzzled, though, as to why preK has these long-term effects. Why, exactly, does the early boost in test scores tend to fade out by 3rd grade, only for preK attendance to result, later on, in better high school graduation rates? What happens in a preK classroom that reduces the likelihood of having a criminal record 20 or 30 years later?

Currently, efforts are underway to piece together two such puzzles — and I’m optimistic that we’ll find answers in the coming years.

Why doesn’t the preK test-score boost last?

The phenomenon of “fade-out” has been well-documented (Bailey et al., 2017). Simply put, children who participate in preK tend to enter kindergarten with higher test scores than do similar children who did not attend, but their advantage fades within the first few years of school, sometimes fully and sometimes partially. By 3rd grade, the scores for both sets of students have converged.

Scholars have offered a number of hypotheses for why this might be the case. For instance, perhaps it has to do with the particular skills preK programs target, when they teach those skills, or what kinds of instruction children receive after preK. Recent evidence suggests that the momentum kids gain from learning “unconstrained skills” (such as reading comprehension and vocabulary) in preK is likely to continue in the early grades, while the advantage from learning “constrained skills” (such as memorizing the alphabet) tends to fade, since it’s easy for kids who don’t attend preK to catch up (McCormick et al., 2021).

There is little question that early childhood programs benefit children both as they move into kindergarten and over the long run.

Other researchers have found that when teachers in the early elementary grades receive high-quality professional support, students are more likely to continue the momentum they gained in preK (Clements et al., 2013). Similarly, one study found that fade-out was less pronounced among children in schools where the curriculum was tightly aligned across the early grades (Jenkins et al., 2018), and this has prompted some school systems to create stronger connections between preK and elementary school. For instance, Boston is retooling its K-2 curriculum to build on the strengths of its preK program, and researchers will be eager to see whether this translates to preK having stronger, longer-lasting effects on children’s academic performance.

What factors influence preK’s effectiveness?

Today, we see considerable variation in the characteristics of public preK programs across the country. For example, some offer only half-day programs while others provide full-day options. Some programs use curricula that independent researchers have found to be of high quality, while others use curricula that have been created in-house or that lack a strong evidence base. Some programs require teachers to have degrees in early child education, and others don’t. And while six states pay their preK educators at parity with their K-12 counterparts (including equal salary, benefits, and compensation for professional development), most states do not.

A number of researchers are exploring whether such variables influence the effectiveness of preK programs. For example, a recent study found significant differences in effectiveness between the full- and half-day programs in a Colorado school district, both of which used a proven language and literacy curriculum. In this randomized control trial, families were offered the opportunity to enroll in either a four-day-per-week program that met for half the day or a five-day-per-week program that met for a full day. Perhaps unsurprisingly, full-day participants had higher language skills at kindergarten entry than did their half-day peers (Barnett & Kasmin, 2017). As studies begin to shed light on differences made by these sorts of program characteristics — scheduling, curriculum and materials, teacher preparation, salary scales, and the like — it should become possible to provide state and federal policy makers with specific guidance on ways to support high-quality learning environments.

The road to universal prekindergarten

As this brief summary shows, there is little question that early childhood programs benefit children both as they move into kindergarten and over the long run. These benefits include not just improvements on cognitive measures but also improved educational attainment, labor market outcomes, and more. In the U.S., however, access to public preK programs still lags far behind our peer nations, particularly for children of color and children from lower-income families. Also, we still have much to learn about why the benefits of early learning often last through adulthood even when we see little evidence of lasting test-score boosts in elementary school. Much of the research today is focused on cracking open this black box to better understand why preK programs work and under what conditions they can be most impactful.

As is true of K-12 education, much of the decision making about how to design, fund, and implement public preK programs is left to state and local policy makers. However, a recent analysis from the National Institute of Early Education Research found that only five states spend enough on early childhood education to pay for high-quality, full-day preK for all children (Friedman-Krauss et al., 2021). The authors estimate that an additional $12 billion are needed to improve the quality of those programs that already exist, and it will take another $30 billion to expand access to these programs to all 4-year-olds in the country. The size of these figures may seem daunting, but at least they give us a clear view of precisely what sort of investment will be required to make universal preK a reality.

 

References

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This article appears in the October 2021 issue of Kappan, Vol, 103, No. 2.