Recent findings from an evaluation of Tennessee’s voluntary pre-k programs have prompted waves of commentary from a host of national and state media. The headlines include words like “shocking,” “bucks conventional wisdom,” “calls into question,” and “Spinach vs. Easter grass” (thanks, NPR). Why all the hubbub?

What the Tennessee Voluntary Pre-k Found

Researchers at Vanderbilt University have been studying the short and longer- term effects of a state funded, voluntary pre-k program for children the year before they enroll in kindergarten. The full report is worth a read, but here is what they have found, very briefly: 

1. Upon kindergarten entry, children attending the pre-K programs scored higher on assessments of math and literacy, and were rated by their kindergarten teachers as more social and behaviorally ready for school than where children who had not attended the public pre-k program. Not a surprise – this effect is pretty consistently reported.

2. Children who were dual language learners seemed to benefit more from the pre-k program. Not a big surprise- other pre-K studies have found similar effects (e.g., Oklahoma public pre-k found immediate effects, and larger effects for Hispanic children).

3. By the end of the kindergarten year, these differences had vanished – children who were not in the pre-k program had “caught-up” with children who had been in the pre-k programs. This continued to be the case at the end of first grade. Not a big surprise – there is evidence of this catch-up effect elsewhere, especially in the Head Start Impact Study.

4. By second grade, children who had not been in the pre-k program were scoring higher than program children on the academic assessments and were rated more positively by their teachers. This was the big surprise.

What might the Tennessee Voluntary Pre-K Study Mean for Early Education

Let’s start with a critical message from the research team: “Our findings on the follow‐up effects of TN‐VPK participation were unexpected. We interpret them cautiously recognizing, as distinguished evaluation researchers have noted, that no single study, no matter how carefully done, produces definitive results. But we would also note that, just because the results of an evaluation do not support a currently popular view, it does not mean that they are wrong” (p. 38). So, let’s consider these findings in the context of other research while also considering how these surprising findings may make sense.

The quality of the program matters.

The authors note that the policies governing the public pre-K program in Tennessee compare favorably against the NIEER benchmarks (See the TN state profile for 2009-2012, the year study children were in pk, here. However, the authors noted that children’s actual experiences varied in quality and certainly, as the program’s enrollment was dramatically increased, the overall quality may have dropped. It is possible that the quality of the public pre-K is high enough to create short-term change, but not sustained impact. Economists Greg Duncan and Katherine Magnuson have published research on the effects of 84 preschool studies that address questions of scale and quality. They find that the effects for “model programs” that are comprehensive and have high per-child funding allocations – Abecedarian and the Perry Preschool/High Scope preschool program for example – were substantially higher than larger-scale programs. All pre- k programs are not created equal.

All of the years from birth through eight matter.

The finding of a substantial but not sustained effect due to pre-k compels us to move away from thinking of high quality pre-K as a “once and done” model for closing early disparities. In considering a similar phenomena among programs designed to help struggling readers, in a 1995 paper, Tim Shanahan and Rebecca Barr introduced this medical analogy:
“early interventions are supposed to operate like a vaccination, preventing all future learning problems, no matter what their source or severity. It appears, however, that early interventions, no matter how successful, are more similar to insulin therapy. That is, substantial treatment effects are apparent right away, but these gains can be maintained only through additional intervention and support” (p. 982)
We need to move away from the inoculation model of early childhood and recognize that while single programs can have immediate effects, the only way to have prolonged impact is to maintain support. As noted in NAEYC’s mission, we must “promote high quality early learning for all children, birth through age 8…” This means a focus on comprehensive services for children before they enter school through 3rd grade, including the critical alignment between pre-K to 3rd grade that the study authors note.

What can we learn from these findings?

A critical lever in the bipartisan –fueled expansion of public pre-k is the knowledge that doing so is a sound economic investment, which is one reason why we see policymakers and parents across the country calling for expanded and increased investments in early childhood education. Studies like this one can help us make these investments count.

As the study authors noted, policymakers should remember that classrooms observed in the study were diverse in their approaches — and that much can still be learned from the classrooms that did see positive impacts on students in later grades. This means that there were classrooms in Tennessee that saw and continue to see positive impacts on students that are both immediate and long-lasting. These findings can add to research in states like Georgia and Oklahoma that have experience in taking public pre-k programs to scale to guide future efforts to move towards larger programs. They will also help us move from broad effectiveness studies to more “realist” evaluations that ask, “what works, for whom, under what circumstances?” The study authors will be conducting further evaluation of 160 VPK classrooms to ascertain what qualities most helped children in kindergarten, first, second and third grades. This data will be deeply valuable to policymakers and program leaders as investment in early childhood continues to expand – and we can’t wait to see what they find.