If there is one thing that everyone knows about policy-relevant research in education, it is this: Participation in high-quality preschool programs (at age 4) has substantial and lasting effects on students’ academic and life success, especially for students from disadvantaged homes. The main basis for this belief is the findings of the famous Perry Preschool program, which randomly assigned 128 disadvantaged youngsters in Ypsilanti, Michigan, to receive intensive preschool services or not to receive these services. The Perry Preschool study found positive effects at the end of preschool, and long-term positive impacts on outcomes such as high school graduation, dependence on welfare, arrest rates, and employment (Schweinhart, Barnes, & Weikart, 1993).
But prepare to be disappointed.
Recently, a new study has reported a very depressing set of outcomes. Lipsey, Farran, & Durkin (2018) published a large, randomized study evaluating Tennessee’s statewide preschool program. 2990 four year olds were randomly assigned to participate in preschool, or not. As in virtually all preschool studies, children who were randomly assigned to preschool scored much better than those who were assigned to the control group. But these results diminished in kindergarten, and by first grade, no positive effects could be detected. By third grade, the control group actually scored significantly higher than the former preschool students in math and science, and non-significantly higher in reading!
Jon Baron of the Laura and John Arnold Foundation wrote an insightful commentary on this study, noting that when such a large, well-done, long-term, randomized study is reported, we have to take the results seriously, even if they disagree with our most cherished beliefs. At the end of Baron’s brief summary was a commentary by Dale Farran and Mark Lipsey, two the study’s authors, telling the story of the hostile reception to their paper in the early childhood research community and the difficulties they had getting this exemplary experiment published.
Clearly, the Tennessee study was a major disappointment. How could preschool have no lasting effects for disadvantaged children?
Having participated in several research reviews on this topic (e.g., Chambers, Cheung, & Slavin, 2016), as well as some studies of my own, I have several observations to make.
Although this may have been the first large, randomized evaluation of a state-funded preschool program in the U.S., there have been many related studies that have had the same results. These include a large, randomized study of 5000 children assigned to Head Start or not (Puma et al., 2010), which also found positive outcomes at the end of the pre-K year, but only scattered lasting effects after pre-K. Very similar outcomes (positive pre-k outcomes with little or no lasting impact) have been found in a randomized evaluation of a national program called Sure Start in England (Melhuish, Belsky, & Leyland, 2010), and one in Australia (Claessens & Garrett, 2014).
Ironically, the Perry Preschool study itself failed to find lasting impacts, until students were in high school. That is, its outcomes were similar to those of the Tennessee, Head Start, Sure Start, and Australian studies, for the first 12 years of the study. So I suppose it is possible that someday, the participants in the Tennessee study will show a major benefit of having attended preschool. However, this seems highly doubtful.
It is important to note that some large studies of preschool attendance do find positive and lasting effects. However, these are invariably matched, non-experimental studies of children who happened to attend preschool, compared to others who did not. The problem with such studies is that it is essentially impossible to statistically control for all the factors that would lead parents to enroll their child in preschool, or not to do so. So lasting effects of preschool may just be lasting effects of having the good fortune to be born into the sort of family that would enroll its children in preschool.
What Should We Do if Preschool is Not Magic?
Let’s accept for the moment the hard (likely) reality that one year of preschool is not magic, and is unlikely to have lasting effects of the kind reported by the Perry Preschool study (and no other randomized studies.) Do we give up?
No. I would argue that rather than considering preschool magic-or-nothing, we should think of it the same way we think about any other grade in school. That is, a successful school experience should not be one terrific year, but fourteen years (pre-k to 12) of great instruction using proven programs and practices.
First comes the preschool year itself, or the two year period including pre-k and kindergarten. There are many programs that have been shown in randomized studies to be successful over that time span, in comparison to control groups of children who are also in school (see Chambers, Cheung, & Slavin, 2016). Then comes reading instruction in grades K-1, where randomized studies have also validated many whole-class, small group, and one-to-one tutoring methods (Inns et al., 2018). And so on. There are programs proven to be effective in randomized experiments, at least for reading and math, for every grade level, pre-k to 12.
The time has long passed since all we had in our magic hat was preschool. We now have quite a lot. If we improve our schools one grade at a time and one subject at a time, we can see accumulating gains, ones that do not require waiting for miracles. And then we can work steadily toward improving what we can offer children every year, in every subject, in every type of school.
No one ever built a cathedral by waving a wand. Instead, magnificent cathedrals are built one stone at a time. In the same way, we can build a solid structure of learning using proven programs every year.
Baron, J. (2018). Large randomized controlled trial finds state pre-k program has adverse effects on academic achievement. Straight Talk on Evidence. Retrieved from http://www.straighttalkonevidence.org/2018/07/16/large-randomized-controlled-trial-finds-state-pre-k-program-has-adverse-effects-on-academic-achievement/
Chambers, B., Cheung, A., & Slavin, R. (2016). Literacy and language outcomes of balanced and developmental-constructivist approaches to early childhood education: A systematic review. Educational Research Review 18, 88-111.
Claessens, A., & Garrett, R. (2014). The role of early childhood settings for 4-5 year old children in early academic skills and later achievement in Australia. Early Childhood Research Quarterly, 29, (4), 550-561.
Inns, A., Lake, C., Pellegrini, M., & Slavin, R. (2018). Effective programs for struggling readers: A best-evidence synthesis. Paper presented at the annual meeting of the Society for Research on Educational Effectiveness, Washington, DC.
Lipsey, Farran, & Durkin (2018). Effects of the Tennessee Prekindergarten Program on children’s achievement and behavior through third grade. Early Childhood Research Quarterly. https://doi.org/10.1016/j.ecresq.2018.03.005
Melhuish, E., Belsky, J., & Leyland, R. (2010). The impact of Sure Start local programmes on five year olds and their families. London: Jessica Kingsley.
Puma, M., Bell, S., Cook, R., & Heid, C. (2010). Head Start impact study: Final report. Washington, DC: U.S. Department of Health and Human Services.
Schweinhart, L. J., Barnes, H. V., & Weikart, D. P. (1993). Significant benefits: The High/Scope Perry Preschool study through age 27 (Monographs of the High/Scope Educational Research Foundation No. 10) Ypsilanti, MI: High/Scope Press.
This blog was developed with support from the Laura and John Arnold Foundation. The views expressed here do not necessarily reflect those of the Foundation.