Did the case for starting kindergarten later just get stronger?


When is a child ready for kindergarten? Once this was a no-brainer: You just looked at the birthday. Now a convincing new Stanford study adds another consideration—especially if you’re concerned about your child’s attention or hyperactivity.

It’s not your imagination that there are more “big kids” in those little desks. The age at which kids start school has been steadily rising. As many as 20 percent of new kindergarteners are now 6 years old. (Back in 1968, it was a pretty unusual 4 percent.)

As more families choose “kindergarten redshirting” (holding preschoolers back a year), the more everybody else wonders if it’s a good thing they should consider, too. Many K classrooms now have a mix of kids spanning ages 4 to 6.

The “gift of time”?

The new Stanford research paper reports that kids who delay kindergarten entry by a year show dramatically less inattention and hyperactivity—the big traits of ADHD—and have better self control. And this improved ability to self regulate lasted well into later childhood.

Dramatically is a key word. Delaying kindergarten for one year reduced inattention and hyperactivity by 73 percent for children, on average, by the time they reached age 11—and virtually eliminated higher-than-normal scores on these issues.

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Study co-author Thomas Dee, a Stanford Graduate School of Education professor, calls it “some of the most convincing evidence we’ve seen” to support academic redshirting.

That’s important because a lot of earlier research that looked at academics, alone, didn’t find much of a benefit.

Dee and his team looked at extensive data on children in Denmark, where kids all start school in August of the calendar year when they turn 6. The Danish National Birth Cohort is a detailed study that started with 93,000 pregnant women, with periodic follow-ups, most recently when the kids were 11.


A lot of the credit, the researchers believe, goes to…play.

It might sound backward that play makes kids more ready for school, but here’s how it works: Older starters are much more apt to be able to sit still, stay focused longer, pay attention, and control disruptive impulses—traits that tend to add up to school success.

To a big extent, kids hone those skills through the extended playfulness they get from an extra year of preschool, the researchers say. Remember the adage “play is a child’s work”? At age 5, it seems, that’s still developmentally critical. Preschool emphasizes pretend play, which helps with abstract and symbolic reasoning (the banana is a phone, for example), the researchers point out. During play, kids also get practice honing many basic social skills, like controlling their emotions and learning to get along with others.

The bottom line: More play = better social skills = better academic skills.

Starting formal school later is actually the norm in Denmark and many other developed countries, and they’re no slackers in the achievement department.

So is kindergarten at 6 for everyone?

Given that we don’t live in a country where it’s the norm to start at 6 and our system isn’t set up that way, you might consider the Stanford study an important piece of the puzzle on the kindergarten question.

But here are other puzzle pieces to factor in:

  • What’s the cut-off date for your school? Most of us start by doing the math here. The minimum age for enrollment varies by state and program. Many states have been moving up cut-off dates.
  • What’s the kindergarten program like at the school your child would attend? The new Stanford study may say as much about the state of kindergarten as it does about redshirting. “Kindergarten is the new first grade” is a line you hear a lot. Think back to your kindergarten days: Nap mats? Toys? ABCs? Today, that’s more of a preschool picture (and even many preschools are amping up academics). Kindergartens increasingly focus on reading, writing, and math skills—and even testing. In some ways, the Stanford study is strong evidence against academic kindergartens generally: All 5-year-olds could benefit from more time for learning through play (whether in the form of extra preschool or kindergarten curriculum). So if your child’s proposed K class is more play-based, you might be less inclined to delay, Dee says.
  • Is your child showing the basic signs of kindergarten readiness? Be sure to consider more than academic readiness (like an interest in books, counting to 10). Think about language skills, fine motor skills (for holding pencils and scissors), and social skills, too. The Stanford study suggests that kids who are having trouble with social-emotional skills might be better candidates for redshirting.


  • Is your child a boy or a girl? In the Danish study, starting later reduced attention deficit and hyperactivity issues for both boys and girls. But boys have more ADHD.
  • What’s your motive? Educators delicately suggest factoring a little soul-searching into your calculus. You might hope your average-size 5-year-old will, if held out a year, become a Leviathan on the middle-school soccer squad. But he might decide he hates soccer. Check, too, if you’re motivated by anxiety about your child doing well academically. Surprisingly, few studies have found strong academic benefits. Redshirted kids don’t seem to score better on tests, though there’s a debate about whether this research is too old to be relevant to what’s happening today.

Borderline birthday? Just can’t decide?

  • Realize that’s a good problem to have. If your child is the right age, educators say the majority of kids do just fine as 5-year-old (and sometimes 4-year-old, depending on birthdays) kindergartners. That should be a relief to parents who are wary about having to pay for another year of preschool. In fact, some research suggests that the scrappy youngest kids are the ones who benefit most from having older kids in a classroom.
  • Ask your preschool teacher, who not only knows your child well but is familiar with lots of age-mates, a great position for making informed comparisons about readiness. You might also ask your child’s doctor to weigh in.
  • Seek an assessment. Some preschools, school districts, and private educational consultants can do readiness assessments that provide added insight about your child’s maturity and overall abilities.
  • Consider pre-kindergarten. This option is growing in both public and private school systems, thanks to both the redshirting and the academic kindergarten trends. It’s pretty much what 5-year-olds in kindergarten used to do—play and learn basic social skills—back before we had to worry about all this.


Whether you give your child “the gift of a year” or go by the calendar, thinking through the decision with these issues in mind pretty much guarantees one thing: a happy, thriving kid who will eventually become a happy, thriving first grader.

Photos from top: Howard County Library System/Flickr, Tezuka Architects-Fuji Kindergarten 13/Flickr, woodleywonderworks/Flickr

See also:

By | 2017-08-28T08:28:46+00:00 November 13th, 2015|Grade-schooler, Preschooler|

About the Author:

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Content chief Paula Spencer Scott is a mom of 4 and step-mom of 2—and the author or co-author of more than a dozen books about parenting, health, and eldercare, including Bright From the StartThe Happiest Toddler on the BlockLike Mother, Like Daughter; and Surviving Alzheimer’s.


  1. […] and numbers. Unlike here, kindergarten isn’t a state-mandated grade for 5-year-olds (or redshirted 6-year-olds); it’s an optional pre-primary school experience for ages 2 to 6. Picture classic, old-time […]

  2. […] Kinstantly has some tips for how American parents can advocate for waiting an extra year before starting kindergarten. […]

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