Two Studies Provide New Evidence on the Pre-K Fadeout Phenomenon


Prekindergarten programs improve children’s kindergarten readiness. However, children who do not enroll in these programs tend to catch up to the academic and cognitive skills of their prekindergarten-attending peers partially or fully during elementary school.

This pattern of results—described as convergence or fadeout—has led to policy debates about the value of investing in prekindergarten programs. Child Development recently posted two studies led by researchers at MDRC and the University of Michigan, completed in partnership with the Boston Public Schools (BPS) Department of Early Childhood, exploring when and why the benefits of prekindergarten tend to fadeout or converge over time. The BPS prekindergarten program is well-known in the field of early childhood education for being a high-quality program that provides instruction to support children’s development of language, literacy, math, executive functioning, and social-emotional skills.

In the first study, “The Kindergarten Hotspot: Literacy Skill Convergence Between Boston Prekindergarten Enrollees and Non-enrollees,” researchers Christina Weiland, Rebecca Unterman, and Anna Shapiro used a quasi-experimental approach with nearly 5,000 children who applied to the Boston prekindergarten program to determine when fadeout occurred in grades kindergarten through third grade. They found:

  • that enrolling in Boston prekindergarten was associated with substantially higher literacy scores at the start of kindergarten;
  • benefits persisted through the end of third grade, though they were substantially smaller by then; and
  • most of the “catch-up” or “convergence” in literacy skills between enrollees and non-enrollees occurred during kindergarten.

“These results matter because we often lack systematic data on children’s K-2 skills in large-scale systems,” said coauthor Rebecca Unterman from MDRC. “Kindergarten appears to be the key period for future prekindergarten fadeout studies to unpack. Our results also provide further support for the urgency of developing and testing prekindergarten through third-grade models to sustain the prekindergarten boost.”

It’s important to note that the first study occurred before Boston’s reforms to implement approaches to align instruction from prekindergarten through second grade. In the second study, entitled “Is Skill Type the Key to the Pre-K Fadeout Puzzle? Differential Associations Between Enrollment in Pre-K and Constrained and Unconstrained Skills Across Kindergarten,” Meghan McCormick, Christina Weiland, JoAnn Hsueh, Mirjana Pralica, Lillie Moffett, Amanda Ketner, Catherine Snow, and Jason Sachs examined convergence patterns after the reforms and with a richer set of outcome measures. Specifically, they examined associations between enrollment in BPS prekindergarten and children’s constrained and unconstrained language/literacy and math skills in the spring of kindergarten, compared to students who attended another prekindergarten program in the community or did not attend formal prekindergarten at all.

Constrained skills are essential to learn but are competencies that all children are likely to develop quickly when they start school. These include skills that can be directly taught and easily assessed, such as naming the letters of the alphabet, letter sounds, numbers from one to twenty, and counting. In contrast, unconstrained skills—like vocabulary, problem solving, and critical thinking—are limitless and continue to develop across the life course. They are supported through a broad range of activities, like reading, storytelling, and engaging in rich discussions about math concepts, and are more difficult to assess.

The authors of this study found that the benefits of the BPS prekindergarten program were more likely to be sustained for:

  • unconstrained language (vocabulary) skills, compared to constrained literacy skills (letter name and sound recognition, early phonics skills); and for
  • unconstrained math (problem solving, critical thinking) skills, compared to constrained math skills (numeral recognition, counting, simple sums)

Findings suggest that skill type is an important part of the prekindergarten fadeout puzzle and the initial benefits of prekindergarten on unconstrained skills may be more likely sustained across time, compared to constrained outcomes.

“Both studies suggest that there can be lasting effects of a high-quality prekindergarten program,” said Meghan McCormick from MDRC, the lead author of the second paper examining skill type. “However, they highlight the importance of understanding what exactly is happening to particular types of skills during kindergarten, when the majority of prekindergarten fadeout occurs. Prekindergarten programs should seek to balance instruction to support both constrained and unconstrained skills, and researchers should evaluate the effects of programs on both types of outcomes in the short- and longer-term.”