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Does Pre-K Work? Why Measuring Quality Across Years Matters

06 Oct 2015 by Jennifer Park

Preschool programs have been shown by numerous studies to be effective in increasing children’s social and academic achievement by kindergarten entry, so why do we continue to question the value and worthiness of these investments in critical early learning experiences, particularly for more disadvantaged children? Similarly, why would we want to think of preschool as an inoculation? Do we really think we can dose a vulnerable four-year old with nine months of decent early education and voilà they read like the kids from the fast lane?  It’s like we think pre-k “pours in” skills to the container that is a four-year old, and those skills are permanently there, they won’t leak out. We treat this as if the years before preschool and then again the years between preschool and third grade don’t matter.  

Dozens of well-controlled studies show that a year pre-k of decent quality can close the achievement gap by half.  But the dearth of good quality pre-k classrooms, combined with the dearth of high quality, K, 1, and 2 classrooms means the likelihood that a vulnerable child will receive a high quality educational experience across these early years is almost nil. Education is a ground game—what happens in classrooms really matters, and it matters year in and year out. Vulnerable kids need a steady and consistent dose of quality over many years to build up a robust portfolio of knowledge and skills that they can carry forward despite a year in a poor quality classroom. We continue to engage in the wrong argument over and over again—pre-K can and does work—the evidence tells us that vulnerable children can learn at an accelerated pace when they receive a healthy dose of high quality educational and developmentally simulating experiences in a classroom. Unfortunately we can’t guarantee that every vulnerable child lands in a classroom like that. Quality does matter, every year.

Do the Benefits of Pre-K Last?

There continues to be considerable debate around whether positive and sustained benefits are derived from publicly funded early learning programs such as Head Start, subsidized child care, and state prekindergarten programs. Since the advent of these programs, requirements have been defined based on research and exemplar models such as the Perry Preschool Project of the ‘60s and the Abecedarian Project of the ‘70s. While modifications in program requirements have been made with the discovery of newly discovered key factors through efficacy research, conclusions from evaluation studies generate mixed responses to the basic question: do these investments work? 

Decades of research have demonstrated the effectiveness of preschool programs, as measured by gains in achievement from program entry to exit. Children who participated in high quality preschool consistently entered kindergarten more prepared to learn and better positioned for long-term academic success. But demonstrating short-term gains have not been sufficient in justifying continued investments of public funds. In fact, there is a growing demand for additional evidence to understand if and how the positive short-term gains resulting from preschool investments may lead to later school success. The demand for sustained gains through 3rd grade has become the new standard. The emphasis on 3rd grade outcomes is important and underscores the critical importance of taking advantage of learning gains during the preschool year, maintaining these gains, and maximizing potential across a child’s academic career. In terms of program policy, this 3rd grade standard is an advancement that is good for education, keeping the student as the priority rather than a program. However, early learning programs are more frequently being held accountable for 3rd grade test scores, without taking into consideration both the quality of the preschool programs, as well as the quality of the elementary classrooms that children attend after preschool.  

Recently released findings on Tennessee’s Voluntary Prekindergarten program, VPK found that participating children demonstrated greater achievement gains on measures of early literacy, language and math skills than children who did not participate in VPK. Further, upon kindergarten entry, teachers reported VPK participants to be “more ready for school,” as having better “social behavior” and better “work-related skills in the classroom[1].” These findings were both positive and statistically significant pointing to the short-term benefit of participating in VPK.

Understandably, much of the attention has been placed on children’s achievement after kindergarten entry. Wouldn’t it be great if those effects at the end of pre-k somehow translated into the same gains and impacts by third grade? Then all we would need to do is work on the pre-k quality challenge. But, by the end of kindergarten there were no longer significant differences between VPK participants and non-participants and by third grade, VPK participants performed less well than non-participants. These results have been theorized to be due to “fade out” or “catch up” of the control children as demonstrated by 3rd grade achievement, without any assessment or estimate of the role that the quality of instruction played in preschool, or in the early elementary school years.  Is it important to note that Tennessee ranked 44th in the country for K-12 funding by the Education Law Center’s account[2] and 48th by Education Week Quality Counts.[3] How do those pre-k and non-pre-k kids sort themselves into the better and (possibly) mostly worse classrooms in Tennessee’s elementary grades? Should we at least question whether children’s access to quality instruction, particularly once they transition into the public school system, might be part of the equation accounting for these third grade results? Again, do we really think that nine months of decent experiences as a four year old re-sets a developmental trajectory on a completely different course regardless of subsequent experiences? From a developmental point of view, the key to long-term social and academic success is better coordination, alignment and consistent exposure to high quality instruction over children’s entire academic careers. 

Miami Study Finds Pre-K Makes a Difference

In contrast to Tennessee’s evaluation of just more than 3,000 VPK participants are study findings released the following day which included more than 11,000 children participating in publically-subsidized preschool in Miami-Dade County, one of the nation’s most urban and diverse communities, with a population numbers similar to many states in the nation. The Miami School Readiness Project (MSRP)[4] represents a unique, large administrative dataset that was used to study historically underserved, low-income Latino children who participated in preschool programs from 2002 to 2006 and followed these children longitudinally into the public schools. This population is particularly of interest to policymakers in that many studies have found that Latino children often enter kindergarten with lower school readiness skills than their non-Hispanic peers and this achievement gap tends to persist over time.  Thus, efforts to effectively address the achievement gap in the earliest years may help offset this historical pattern of persistently lower achievement throughout the school years.

Like the Tennessee study, the MSRP research included low-income 4-year-olds and found that participation in publically-funded preschool programs yielded short-term gains in pre-academic and social-behaviors skills at kindergarten entry.  However, in contrast to the Tennessee study, the MSRP study found sustained gains through the end of 3rd grade. Participating children performed better on the state-administered third-grade reading comprehension tests (90% pass rate as compared to 86 percent for the overall MSRP sample which included low-income, non-Hispanic black and white children) and exhibited higher GPAs at the end of 3rd grade.

So what do we make of the differences between these two studies? First, as with all research, it is critical to understand limitations for each study. In both studies, researchers set out to understand complex problems with limited available information. The Tennessee evaluation did not measure or control for variations in the level of classroom quality across different VPK programs, a critical factor in understanding specific instructional practices and learning contexts for different children. Likewise, the Miami-Dade Study did not have access to information on teacher characteristics or classroom quality features within programs. Thus, neither study was able to measure or control for program level characteristics or instructional quality as a way to understand the specific benefits to children’s learning experiences and related achievement.  

Another question that should be addressed is what contextual factors existed in each of these communities that may have contributed to the respective pattern of findings? Could Tennessee’s low K-12 per student financing have yielded less-well prepared and unsupported teachers? If children not participating in preschool programs enter kindergarten less prepared than preschool program participants, are Kindergarten teachers compensating by investing more time and effort in supporting the less prepared children allowing them to “catch up?” We just don’t know.

In 2002, Miami voters passed a ballot initiative that led to the creation of a dedicated revenue source for services for children and the formation of The Children’s Trust to oversee and coordinate this revenue source. This independent special district created a dedicated public funding source to create partnerships within the community to improve the lives of all children and families in Miami-Dade County by making strategic early childhood investments. Specific to early learning, the Children’s Trust, in partnership with the Early Learning Coalition and Miami-Dade County Public School District coordinated, planned, and funded quality initiatives to improve classroom practices in early learning programs. Could the passage of this ballot initiative and resulting formation of The Children’s Trust have resulted in added program supports across children’s early care and education programming? Is the passage of this initiative an indication of the communities’ active commitment to supporting children? 

So what are we learning from these studies and what else do we need to do to better prepare children for long-term academic success? Beyond the cursory evaluation of funding and approaching program effectiveness as a “works” or “doesn’t work” framework, we need to better evaluate what specific program features predict long term success. The aforementioned Perry Preschool Project the Abecedarian Study told us how specific approaches to quality in early childhood experiences led to both short- and long-term benefits for children. From these studies, we learned that, quality was defined by formal, structured care with a developmental curriculum and a whole child approach, including parent education and health services leading to positive differences in the trajectory of a child. Then in the ‘80s there were advancements made in the development of early childhood curricula, training, professional development and technical assistance, including the development of the Early Childhood Environmental Rating Scale (now the ERS), the first observational measure used to examine and guide training around aspects of structural quality, or environmental features. Then, in the ‘90s another observational measure, the Classroom Assessment Scoring System (CLASS), was introduced to measure and guide the improvement of process quality, or teacher instructional practices. Today, quality often is described by the use of effective teaching practices guided by research-based curricula and child assessments, within a framework of environmental quality and delivered by teachers demonstrating key competencies. When examining the effectiveness of preschool programs, one must do so by including quality measures that have strong measurement properties, including predictive validity, having evidence from prior research that positive performance on the measure has been shown to yield positive outcomes for children.

Needed: A Measure of Program Quality

Why do some studies measure child outcomes over time without measuring program quality over that same duration? In both the TN and Miami studies, it would be helpful to learn more about what specific features of classroom quality may have led to short-term gains for 4-year-olds and what program features continued or did not persist into elementary school. There are quality measures such as the ERS and CLASS that are used in most research and accountability models. In addition to measuring global quality, researchers also should assess teacher preparedness and competencies, as well as adherence to curricular and assessment models. It is not until we examine these factors that we can more accurately attribute any success or failure of preschool programs’ contributions to 3rd grade performance. In any program evaluation the goal is to determine whether the program was effective in reaching its intended goal. Preschool program goals often include the following: (1) show measureable gains beyond what we would expect over non-participating counterparts; and (2) develop the knowledge, skills and abilities in children to be ready for kindergarten.

Continuing to hold preschool programs accountable for 3rd grade achievement is much like holding high schools accountable for college graduate rates. We don’t do this. In fact, we hold high schools accountable for 12th grade achievement and college entry rates, much like preschool programs should continue to be held accountable for end of year achievement and kindergarten readiness.  Thus, both the TN and Miami studies have added new knowledge to the ongoing debates about the effectiveness of publically funded preschool.  However, we hope that the studies also contribute to the discussions about both the importance of ensuring the design and funding of the highest quality preschool programs as well as the appropriate funding of the most rigorous and comprehensive evaluations to ensure the appropriate examination of the accountability of the investment of public resources.


[1] https://my.vanderbilt.edu/tnprekevaluation/files/2013/10/August2013_PRI_Kand1stFollowup_TN-VPK_RCT_ProjectResults_FullReport1.pdf

[2] http://www.schoolfundingfairness.org/National_Report_Card_2015.pdf

[3] http://www.edweek.org/media/school-finance-education-week-quality-counts-2015.pdf

[4] http://www.childtrends.org/wp-content/uploads/2015/09/Hispanic-Center-MSRP-Brief-FINAL.pdf

About the Co-Author: 

Dr. Michael L. López is a contributing author on this blog. He is a nationally renowned authority on the development, education and well-being of young children, including low-income and culturally and linguistically diverse populations.  As a principal associate in the Education Practice, Lόpez leads the new National Research Center on Hispanic Children and Families, in partnership with Child Trends.  The Center is dedicated to providing research findings and tools to advance the capacity of the field to serve Hispanic children and families. See more.


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