Persistence and Convergence: The End of Kindergarten Outcomes of Pre-K Graduates and Their Nonattending Peers

The pre-K study that you asked about that was noted inWSJ, they don’t actually seem to think pre-K has that much salience as the article seemingly implied, in that non-attenders (in terms of pre-K) make greater gains then attenders in Kindergarten even though the Pre-K grads enter kindergarten with greater skills versus the non-grads. So pre-K does work, but then people catch up. They don’t say if the residual (50%) gains from pre-K get closed further over out years.

Here is core result, “…The present investigation examined the benefits of pre-K through the end of kindergarten for children from low-income homes who lived in a large and diverse county (n = 2,581) as well as factors associated with a reduction in benefits during the kindergarten year. Results revealed that pre-K graduates outperformed nonattenders in the areas of achievement and executive functioning skills at the end of kindergarten, and also that the benefits of pre-K at the start of the year diminished by a little more than half. This convergence between groups' performance was largest for more constrained skills, such as letter-word identification, and was attributed to the fact that nonattenders made greater gains in kindergarten as compared with graduates of pre-K. Importantly, convergence in the groups' performance in kindergarten was not attributed to pre-K children's classroom experiences in kindergarten. Convergence was, however, attributable to preexisting individual differences, andthere was support for the notion that even though children's skills are susceptible to improvement as a result of pre-K, their longer-term outcomes are likely to be impacted by factors that are outside the scope of early schooling….”

Arya Ansari, Robert Pianta, Jessica Whittaker, Virginia Vitiello, and Erik Ruzek, "Persistence and Convergence: The End of Kindergarten Outcomes of Pre-K Graduates and Their Nonattending Peers,"Developmental Psychology, October 2020, https://pubmed.ncbi.nlm.nih.gov/33017159/

Note this on long term benefits, “…Accordingly, although the results clearly indicate that the benefits of pre-K persist at least 12 months after program completion,these results also support the view that targeting malleable skills that would develop absent of pre-K (or other types of early intervention) is insufficient for generating sizable long-term benefits, in part because many of these skills are likely to develop rapidly among nonattenders shortly after school entry…..That is, for the benefits of pre-K to persist, these benefits must be sizable, the skills children learn in pre-K must matter in relation to learning subsequent skills, and these skills should not develop at a fast rate among nonattenders upon kindergarten entry…”

To quote the report, “…In conclusion, the results reported herein appearconfirm two patterns of results detected in a number of studies—the benefits of pre-K indeed do persist through the end of kindergarten, and asubstantial share of these benefits diminish in the year after program exit.In short,the differential benefits converge.Moreover, it does not appear that children’s experiences in kindergarten contribute to convergence, at least in this study sample. For future studies to understand why pre-K graduates demonstrate fewer gains in kindergarten as compared with their peers who are just entering school for the first time will require closer and more comprehensive inspection of children’s experiences in the year after program completion….”

The study found that pre-K graduates entered kindergarten with greater academic and executive function skills as compared with children who did not attend pre-K at age 4, but no consistent differences emerge for their social skills. However these academic and executive function advantages are cut in half by the end of kindergarten because, even though all children make gains in kindergarten, non-attenders make greater gains, especially with respect to more constrained skills, "..That is, the associations between pre-K enrollment and the child outcomes of interest were significantly smaller by the end of the kindergarten year as compared with the start of the school year. On average, the associations between pre-K enrollment and children’s academic achievement and executive functioning shrunk by approximately 55- 60%.Convergence was largest for children’s letter word identification skills (roughly 80%) and smallest for children’s language and general knowledge skills (roughly 45%). When decomposing these estimates, we find that convergence in the benefits of pre-K, at least with regard to differences in performance between attenders and nonattenders, was largely attributable to “catch-up.”All children (regardless of pre-K participation) demonstrated improvements in their academic and executive function skills in kindergarten; however, pre-K graduates made smaller improvements than their peers who did not attend pre-K. There was also evidence to suggest that children’s socioemotional skills were changing differentially during the kindergarten year as a function of pre-K attender status (p.01). When decomposing these estimates, we found that although teachers reported that nonattenders demonstrated improvements along this dimension of development across the kindergarten year, they did not report similar improvements in pre-K attenders’ socioemotional skills..."

So from my read of the study pre-K seems to "pull forward" many benefits on kindergarten, “…Put another way, a little more than half of the original advantage associated with attending pre-K at the age of 4, relative to not attending, appeared gone seven to eight months later….”