Long-term Impacts of Universal Pre-K—Understanding Conflicting Research

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Research Summary 11
Spring 2024

Recent research from the Tennessee Pre-K longitudinal evaluation has generated interest, concern, and discussion about the long-term impacts of Pre-K on children and school performance, according to an article titled, “Effects of a Statewide Prekindergarten program on Children’s Achievement and Behavior through Sixth Grade,” published in Developmental Psychology, a peer-reviewed journal. With a nationwide increase in state-funded Pre-K programs over the past 40 years, a Brookings Institute’s study, “Expectations of sustained effects from scaled up Pre-K: Challenges from the Tennessee”, reports that now nearly a third of all 4-year-olds attend a state funded Pre-K program and evaluations are trying to catch up to provide an understanding of the long-term impacts.

Research on early childhood education has been extensive and has demonstrated the importance of high-quality early childhood education on long-term child development and academic achievement. Recent studies, however, have shown mixed results. Much of this research was conducted several years ago in targeted and structured high-quality child care programs that included a focus on health and well-being, family engagement, and hands-on learning opportunities. Research on universal and statewide Pre-K programs is more varied and involves more intensive implementation than other programs, according to Brown University ED Working Paper No. 23-885 titled, Why are Preschool Programs becoming Less Effective?

This research brief reviews the findings from some of the most recent evaluations of universal state and local Pre-K programs. Current research across multiple studies has shown that the effects of Pre-K lessen or fade over time. However, a Policy Brief for Education Commission of the States titled Exploring New Research on Pre-K Outcomes reports that studies have found different patterns in the fade out and in the long term impacts. This review includes potential factors that could explain the different evaluation findings, community recommendations based on the existing research, and key factors to consider related to the long-term impacts of Pre-K for communities. This review of other literature also informs understanding of the landscape prior to the review of the Georgia evaluation later this year.

Findings from Recent Longitudinal Pre-K Evaluations

Only Georgia, North Carolina, Tennessee, and Boston have engaged in major evaluations looking at the long-term impacts of state sponsored Pre-K programs. Early evaluations show that initial gains and kindergarten teacher perceptions found that Pre-K students were better prepared than non-Pre-K students. Much of the research on the impacts of Pre-K have not utilized randomized assignment and comparison groups. This means the research could only look at the outcomes for the children in Pre-K but could not compare how those students did, compared to students who did not experience Pre-K. Controlled, comparison, longitudinal studies on universal Pre-K have not been able to keep up with the fast expansion of these types of statewide universal programs and existing research has yielded conflicting findings on the long-term impacts of universal Pre-K programs.

We will only understand more completely the impacts of Pre-K on long term outcomes by examining outcomes for control groups, randomizing assignment to Pre-K participation, and looking at long-term outcomes for control groups and Pre-K attendees. Without these comparisons, it isn’t possible to know if the outcomes are due to Pre-K or to other factors like community environment, school, individual development, or home environments.  Georgia is leading the nation in universal Pre-K programs and is implementing a comprehensive long-term longitudinal evaluation of the program Georgia Department of Early Care and Learning’s (DECAL) “Longitudinal Study of Georgia’s Pre-K Program: Pre-K through 4th Grade”.

Durkin and colleagues (2022) examined the results of a longitudinal randomized control study of the Tennessee statewide Pre-K program.  The goal of the TN program is to increase school readiness prior to kindergarten entry particularly for low-income families.  They looked at outcomes for almost 3,000 children from low-income families.  Children who were randomly assigned to attend Pre-K had lower state achievement test scores at 3rd and 6th grades than those who did not attend Pre-K.  The negative effects increased over time with larger differences seen at 6th grade than the earlier periods.  Pre-K students showed higher disciplinary infractions, poorer attendance, and greater receipt of special education services.  It was noted that the greater use of special education may have been due to earlier identification of needs and services.

While Pre-K students were performing better than non-participants during Pre-K and immediately after, those gains started to fade during kindergarten and by the end of 3rd grade, Pre-K participants were scoring lower than non-participants in math and science and having higher rates of school disciplinary actions. One factor that did change this was when students attended higher quality schools and had higher quality teachers. Pre-K students were also cited by teachers and on test scores to be doing better than non-Pre-k students during the program and immediately after, but these differences faded by the end of kindergarten. Test scores showed initial increases at a faster rate for Pre-K students but faded over time and by age 9, Pre-K attendees were not performing as well as other students.

An evaluation of a universal Pre-K program in Boston showed positive results from 1999 to 2003. While there were no differences in elementary school test scores, Pre-K students were more likely to graduate from high school, have higher SAT scores, fewer disciplinary problems, and higher college attendance rates. More recent studies show that cohorts are showing null effects at third grade and evaluations continue to examine longer term impacts.

In his presentation to the Michigan State Board of Education titled, “The long-run effects of high-quality Pre-K: What does the research show?” Tim Bartik of WE Upjohn Institute for Employment Research points out that this study, as well as additional research on North Carolina and other early care and education research reveals that the greatest long-term impacts are seen on individual adult outcomes even more than in school test scores. Effects that fade in elementary school often reemerge in high school and later adult outcomes.

Georgia’s longitudinal study has found that most positive outcomes level off in 1st grade and decrease or stabilize through 3rd grade but there has been a small increase in 4th grade in literacy, math, and social skills. These findings indicate that continuing to follow the long-term impacts is essential. Pre-K students had better language, literacy, and executive functioning skills than those who did not participate. The findings for this longitudinal study are consistent with other research that demonstrate that while impacts may fade during elementary school, long term impacts re-emerge in high school and adulthood.

The initial evaluation in North Carolina indicated that Pre-K students leave Pre-K with higher language and early reading skills but that these advantages were fading by the end of kindergarten. Increasing funding for the program had positive impacts particularly for severely disadvantaged students, according to Brown University’s ED Working Paper. The recently released update to the Georgia Pre-K evaluation showed significant gains in math and reading at the end of Pre-K but that these changes were fading by 4th grade.

A recent study in Oklahoma focused on the impact of a universal Pre-K program and found that students who attended Pre-K had higher standardized scores and lower rates of grade retention than those who did not attend Pre-K. In the Tulsa study, Pre-K attendance was associated with lower rates of grade retention and less absenteeism, less likelihood to fail, and more likely to take AP classes. These outcomes, according to a Society for Research in Child Development article titled, “Does early childhood education help to improve high school outcomes? Results from Tulsa,” were most pronounced and sustained for black, Hispanic, and Native American students.

The Head Start research and longitudinal studies have found positive impacts for cohorts who participated in the program prior to 1990, however more recent cohorts have shown null or negative impacts on participants in early adulthood. The positive impacts of the program fade over time and by third grade there were few different.

Adrienne Fischer and colleagues in aPolicy Brief for Education Commission of the States titled, Exploring New Research on Pre-K Outcomes, reviewed 37 articles on the impact of Pre-K programs over long and short term. While there were positive effects across all the articles, many also found converging or ‘fade out’ effects where there was no impact, or the impact of Pre-K participation disappeared over time. The number of positive effects was significantly larger than the converging effects. Executive functioning had the greatest number of converging effects over time.

Factors Influencing Conflicting Findings

Meta research reviews and other articles are examining why the effects found in studies differ and how we can work to improve effectiveness of Pre-K programs. Some factors include the increasing expansion of community-based early care and education (childcare) and increasing use of these programs and the expansion of family support programs that help to create richer early childhood environments. The researchers who contributed to the Brown University ED Working Paper also cite the increasing use of high-quality center-based care. They point to the lack of randomized controlled studies examining the long-term impacts of Pre-K due to costs and ethical challenges. Other potential sources of research limitations include the lack of a pre-test or baseline for control groups in studies where they are looking at matched groups and performance over time, according to the Developmental Psychology article.

Fischer and colleagues point out that the variability in quality from program to program and from Pre-K to early elementary can impact the results found by longitudinal studies. An article titled,  “Will Public Pre-K really close achievement gaps? Gaps in Prekindergarten quality between students and across states,” published in the American Educational Research Journal, points out that the quality of the Pre-K classroom is critical to determining the impact on children over time. This can be challenging in statewide universal programs to a greater extent than in the smaller more focused programs that were the focus of much of the early childhood education impact studies. There are quality gaps in public Pre-K programs between low-income and minority students and higher income and non-minority students. States with higher levels of residential segregation (by income and race) were found to have greater gaps and variability in Pre-K quality. These factors can have significant impacts on the long-term impacts of Pre-K on children and families. The Brookings Institute’s study pointed out that the TN program does not require teacher assistants to have a CDA. The Tulsa OK program had low teacher-student ratios, highly trained and well-paid teachers, a state adopted curriculum and was funded like a public-school program and demonstrated long term positive outcomes on students.

The changes in how Pre-K programs have shifted educational experiences was offered as a potential consideration for why there maybe fade out effects. The shift from more hands-on learning activities to teacher managed instruction may be contributing to the fade out and shifts. More recent studies have shown that more time in hands-on-learning opportunities and less time in teacher led large group instruction on basic academic skills leads to more long-lasting and positive outcomes for children over time. Some research studies indicated that Pre-K has transitioned from more hands-on-learning and play based activities to more teacher-led large group instruction. Early Head Start and Pre-K programs included a focus on health, language, and social skills as well as family involvement. The Brookings Institute’s study points out that long-term gains were more frequently found in studies of programs that had more intensive home visits, greater family engagement, longer program hours, more health focus, and lasted for a longer period of time overall.

Universal Pre-K programs have shown higher test score effects than income targeted preschool programs. The Georgia and North Carolina programs are universal, while the Tennessee Pre-K program is specifically targeted to low-income families with income constraints on eligible participants.

Implications and Recommendations

Following are some recommendations based on the research:

  • Continue to examine the factors, types of learning, and quality of care factors that are related to more positive and long-lasting impacts for children.
  • Examine classroom characteristics and interactions that are linked to improvements in unconstrained skills, including problem solving, mathematical reasoning, listening comprehension, and background knowledge.
  • Focus on more internal self-control rather than teacher- and classroom-directed control and focus.
  • Including health factors and family engagement in Pre-K programs more extensively.
  • Focusing on language, executive functioning, and social skills rather than rote skills.
  • Increasing educational requirement for teachers and teacher assistants as well as ongoing professional development.
  • Aligning Pre-K quality with early elementary quality.
  • Ensuring high-quality Pre-K classrooms, curriculum, and developmentally appropriate practices.
  • Providing universal Pre-K to all students, regardless of income need or other factors.

Bill Valladares
GaFCP Communications Director

Reg Griffin
DECAL Communications Director

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Bright from the Start: Georgia Department of Early Care and Learning (DECAL) is responsible for meeting the child care and early education needs of Georgia’s children and their families. It administers the nationally recognized Georgia’s Pre-K Program, licenses child care centers and home-based child care, administers Georgia’s Childcare and Parent Services (CAPS) program, federal nutrition programs, and manages Quality Rated, Georgia’s community powered child care rating system.

The department also houses the Head Start State Collaboration Office, distributes federal funding to enhance the quality and availability of child care, and collaborates with Georgia child care resource and referral agencies and organizations throughout the state to enhance early care and education.