How long does the preschool advantage last?

"Ensuring that young children enter kindergarten ready to learn has been of great research and policy interest. By all accounts, pre-K programs have helped achieve this goal," said Arya Ansari, PhD, of The Ohio State University and lead author of the study, published in the journal Developmental Psychology. "However, there have been lingering questions as to whether contemporary and scaled-up pre-K programs provide children with enduring benefits as they progress throughout their educational careers."

The researchers studied 2,581 children enrolled in kindergarten in a large, ethnically diverse county. All the participants were from low-income families that would qualify for Head Start or another subsidized preschool program. Slightly more than half (1,334) attended a preschool program while the rest did not. The researchers assessed the children on their academic skills (e.g., literacy and math), executive functioning (a set of mental skills that includes working memory, flexible thinking and self-control) and socioemotional skills deemed important to academic success. The assessments were conducted at the start of the kindergarten year and again in the spring.

"We found that pre-K graduates entered kindergarten demonstrating stronger academic skills than those who did not attend preschool. The same was true for executive functioning, but there was no aggregate difference in kindergarten teachers' reports of their socioemotional skills," said Ansari. "However, we also found that the differences between attenders and nonattenders diminished between the fall and spring of kindergarten, primarily because nonattenders who entered school for the first time in kindergarten made larger learning gains as compared with their classmates with pre-K experiences."

These differences in progress during kindergarten were not uniform across the board but varied by skillset, according to Ansari. For example, for children who did not attend preschool, approximately 80% of the difference in scores for literacy skills was erased over the course of the academic year, but this was the case for only 55% of the difference in math skills and 45% of the difference in vocabulary and general knowledge skills.

"It is important to emphasize that 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," said Ansari.

The research was only done with students from low-income families because other research shows that they enter kindergarten at a disadvantage academically, and significant public investment has been made to provide access to preschool programs to address these gaps, according to Ansari. Therefore, caution is required when trying to generalize the findings to higher-income families, he said.

"One interesting part of our findings was that children's classroom experiences in kindergarten had little to do with whether the benefits of pre-K persist over time," he said. "Instead, what our findings appear to suggest is that even though children's skills are susceptible to improvement as a result of pre-K, their longer-term outcomes are likely to be affected by factors that are outside the scope of early schooling. We need to view pre-K as one of many investments we make to ensure that all children have an equal opportunity to succeed in life."

He suggests future research should focus on understanding why pre-K graduates demonstrate fewer gains in kindergarten as compared with their peers who are just entering school for the first time. That research, he says, will require closer and more comprehensive inspection of children's experiences during the kindergarten year.