How Does Kindergarten Entry Age Affect Student Achievement?

The Reference Desk has recently received many questions on kindergarten and how the age of school entry affects student achievement. This week’s digest focuses on how academic “redshirting” (delayed school entry) and early entry affect student outcomes.

Question

How does kindergarten entry age affect student achievement?

Research Synthesis

Reference Desk researchers found many resources that address the age of kindergarten entry. The research on appropriate school entry age shows mixed results. One study found that “being a year younger at entry raises the probability of repeating kindergarten, first, or second grade by 13.1 percentage points … Similarly, being a year younger at entry raises the probability of being diagnosed with Attention Deficit/Hyperactivity disorder by 2.9 percentage points” (Elder, 2009; see below). Another study found that “children who entered kindergarten at younger ages had higher (estimated) scores in kindergarten on the Woodcock-Johnson (W-J) Letter-Word Recognition subtest but received lower ratings from kindergarten teachers on Language and Literacy and Mathematical Thinking scales” (NICHD, 2007; see below). The authors also stated that research “has indicated that relatively older children have a modest academic advantage over younger ones in the first few grades of school, but that this advantage typically disappears … Moreover, there is no evidence that children who enter school at younger ages gain less from early school experience than children who begin at an older age” (NICHD, 2007; see below).

Publicly Available Resources

Age of Entry to Kindergarten and Children’s Academic Achievement and Socioemotional Development. 2007; NICHD Early Child Care Research Network; Early Education Development; Vol. 18, No. 2; pp. 337–368; ERIC Document #EJ772209.
This paper analyzed data on more than 900 children participating in the National Institute of Child Health and Human Development Study of Early Child Care to examine the effect of age of entry to kindergarten on children’s academic achievement and socioemotional development. The authors found that “children who entered kindergarten at younger ages had higher (estimated) scores in kindergarten on the Woodcock-Johnson (W-J) Letter-Word Recognition subtest but received lower ratings from kindergarten teachers on Language and Literacy and Mathematical Thinking scales. Furthermore, children who entered kindergarten at older ages evinced greater increases over time on 4 W-J subtests (i.e., Letter-Word Recognition, Applied Problems, Memory for Sentences, Picture Vocabulary) and outperformed children who started kindergarten at younger ages on 2 W-J subtests in 3rd grade (i.e., Applied Problems, Picture Vocabulary)” (p. 1). “Research … has indicated that relatively older children have a modest academic advantage over younger ones in the first few grades of school, but that this advantage typically disappears. The results of studies following [a different] strategy have also indicated a modest but temporary advantage for older children” (p. 4).
Kindergarten Entrance Age and Children's Achievement: Impacts of State Policies, Family Background, and Peers. 2009; Elder, T. E. & Lubotsky, D. H; The Journal of Human Resources; Vol. 44, Issue 3; pp. 641-683; ERIC Document #EJ846140.
From the Abstract: “We present evidence that the positive relationship between kindergarten entrance age and school achievement primarily reflects skill accumulation prior to kindergarten, rather than a heightened ability to learn in school among older children. The association between achievement test scores and entrance age appears during the first months of kindergarten, declines sharply in subsequent years, and is especially pronounced among children from upper-income families, a group likely to have accumulated the most skills prior to school entry. Finally, having older classmates boosts a child’s test scores but increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD” (p. 2). The authors also found that “being a year younger at entry raises the probability of repeating kindergarten, first, or second grade by 13.1 percentage points, a sizeable effect relative to the 8.8 percent baseline retention rate. Similarly, being a year younger at entry raises the probability of being diagnosed with Attention Deficit/Hyperactivity disorder by 2.9 percentage points, which is also large relative to the 4.3 percent baseline diagnosis rate” (p. 6). The authors caution that their “research design estimates the relationship between entrance age and outcomes based only on the first two sources of variation … by contrast, parental decisions to delay or expedite their child’s kindergarten entry are almost certainly related to other characteristics of parents and children. For example, children who begin kindergarten early are likely to be particularly skilled or gifted, while parents of children with developmental problems are likely to delay their children’s enrollment” (p. 13).
At What Age Should Children Enter Kindergarten? A Question for Policy Makers and Parents. 2002; Stipek D.; Society for Research on Child Development; Vol. XCI, No. 2; 20 pages.
From the Summary Section: “Research that bears on the issue of school entry policies is summarized in this report. The focus is on the age children should be to enter kindergarten and the potential benefits of delaying school entry for all or some children. … There was no evidence suggesting that younger children gained less than older children from early school experience, and some evidence suggested that school experience produced greater gains on most cognitive dimensions. Generally, the findings reviewed provide more support for early educational experience to promote academic competencies than for waiting for children to be older when they enter school. The author suggests that the focus should be more on making schools ready for children than on making children ready for school” (p. 1).

The Reference Desk also found this organization and its resources helpful in learning more about kindergarten issues in general:

Education Commission of the States (ECS): Kindergarten Issue Page
From the website: “The Education Commission of the States (ECS) is an interstate compact created in 1965 to improve public education by facilitating the exchange of information, ideas and experiences among state policymakers and education leaders.” ECS provides an issue page devoted to “Kindergarten” that includes selected research and readings on school entry age.

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