Dale C. Farran and Mark W. Lipsey, Brookings, October 8, 2015
State investments in center-based school readiness programs for preschoolers (pre-K), whether targeted for poor children or universally implemented, have expanded more rapidly than evaluations of their effects. Given the current interest and continuing expansion of state funded pre-K, it is especially important to be clear about the nature of the available evidence for the effectiveness of such programs. Despite widespread claims about proven benefits from pre-K, there is actually strikingly little credible research about the effectiveness of public pre-K programs scaled for statewide implementation.
Like many states that became interested in scaling up a state funded pre-K program in the early 2000’s, voluntary pre-K (TNVPK) was introduced in Tennessee in 1996 as a way to provide academic enhancement to economically disadvantaged children. It expanded in 2005 to an $85 million-plus statewide investment serving 18,000 Tennessee income-eligible children in 935 classrooms across all 95 counties.
Launched in 2009, the TNVPK Effectiveness Study, a coordinated effort between Vanderbilt’s Peabody Research Institute and the Tennessee Department of Education, is a five-year evaluation study funded by the US Department of Education, Institute for Education Sciences. It includes the first randomized control trial of a scaled up state funded pre-K program and the first well-controlled comparison group study of the effects of program participation as children progress through elementary school.
Policymakers and proponents often cite some of the famous early studies of pre-K programs that have shown long term benefits extending into adulthood for the participating children. But those were studies of especially complex programs that are unlike scaled-up public pre-K in many ways. The Vanderbilt study is the first rigorous controlled longitudinal study to be conducted on a large-scale state-funded pre-K program.
This report presents findings from the full evaluation report, available online, summarizing the longitudinal effects of TNVPK on pre‐kindergarten through third grade achievement and behavioral outcomes for a sample of 1076 children, of which 773 attended TNVPK classrooms and 303 did not. Both groups have been followed since the beginning of the pre‐k year. Children in VPK classrooms made initial strong gains and were perceived by their teachers at kindergarten entry as being better prepared. The achievement of the control children caught up to that of the pre-K children by the end of kindergarten. In second and third grades achievement trends crossed over, with academic achievement for the pre-K children becoming worse than for the control children.
The results from this substudy are reviewed in the context of the difficulties of determining the sustained effectiveness of statewide pre-K programs when those programs have been defined so differently state to state and when the evidentiary base from other current studies is so weak.
In sum, it would be shortsighted of pre-K advocates to dismiss the TNVPK study merely as an indictment of the quality of the Tennessee program. Rather the findings from this most methodologically rigorous study to date raise important questions about what is happening all over the country. The benefits of pre-K intervention are being pushed without taking time to define what pre-K really means and, worse, to determine whether what has been implemented has produced the promised outcomes. It is time to take a step back and to figure out what really can and should be scaled up and then how to make that vision happen with consistency and the desired results.
Even if we get the quality right, however, and implement a new vision of scaled up pre-K with consistency, and even if this results in children gaining more from pre-K than they have so far, we still need to question the presumption that pre-K alone will fix the problems poor children encounter in schools. The income-related achievement gap Reardon and others have identified does not exist solely because children do not have a pre-K experience or even a “high quality” pre-K experience. There are other important factors at play including increasing income segregation in the public schools and the low quality of schools serving the poor.