Youngest Kid, Smartest Kid?

When the Harvard sociologist Hilary Levey Friedman was expecting her first child, one thing worried her: her due date, January 3rd. It was uncomfortably close to January 1st, an often-used age cutoff for enrollment in academics and sports. “I was determined to keep him in until after January 1st,” she said. And if the baby came early? “I actively thought about redshirting,” she said. Given the choice, she wanted him to be the oldest kid in his class, not the youngest.

Redshirting is the practice of holding a child back for an extra year before the start of kindergarten, named for the red jersey worn in intra-team scrimmages by college athletes kept out of competition for a year. It is increasingly prevalent among parents of would-be kindergartners. In 1968, four per cent of kindergarten students were six years old; by 1995, the number of redshirted first- and second-graders had grown to nine per cent. In 2008, it had risen to seventeen per cent. The original logic of the yearlong delay is rooted in athletics: athletes who are bigger and stronger tend to perform better, so why not bench the younger, smaller ones for a year? The logic was popularized in “Freakonomics,” in which the authors, Stephen J. Dubner and Steven D. Levitt, pointed out that élite soccer players were much more likely to have birthdays in the earliest months of the year—that is, they would have been the oldest in any group of students that used a January 1st cutoff for enrollment.

On the surface, redshirting seems to make sense in the academic realm, too. The capabilities of a child’s brain increase at a rapid pace; the difference between five-year-olds and six-year-olds is far greater than between twenty-five-year-olds and twenty-six-year-olds. An extra year can allow a child to excel relative to the younger students in the class. “Especially for boys, there is thought to be a relative-age effect that persists across sports and over time,” said Friedman. “Early investment of time and skill developments appears to have a more lasting impact.” Older students and athletes are often found in leadership positions—and who can doubt the popularity of the star quarterback relative to the gym-class weakling?

It’s this competitive logic, rather than genuine concern about a child’s developmental readiness, that drives redshirting. Many parents decide to redshirt their children not because they seem particularly immature or young but because they hope that the extra year will give them a boost relative to their peers. In light of modern competitive demands, why wouldn’t you want your child to have that edge? The psychologist Betsy Sparrow calls it “gaming the system”—and the data on who chooses to redshirt bears out that classification: the people most likely to redshirt their children are those who can most afford to do so—that is, the white and the wealthy. Families in the highest socioeconomic quintile are thirty-six per cent more likely to redshirt their children than those in the lowest, and while close to six per cent of white children are redshirted, the figure falls to two per cent for Hispanic children, and less than one per cent for their black peers.

The data, however, belies this assumption. While earlier studies have argued that redshirted children do better both socially and academically—citing data on school evaluations, leadership positions, and test scores—more recent analyses suggest that the opposite may well be the case: the youngest kids, who barely make the age cutoff but are enrolled anyway, ultimately end up on top—not their older classmates. When a group of economists followed Norwegian children born between 1962 and 1988, until the youngest turned eighteen, in 2006, they found that, at age eighteen, children who started school a year later had I.Q. scores that were significantly lower than their younger counterparts. Their earnings also suffered: through age thirty, men who started school later earned less. A separate study, of the entire Swedish population born between 1935 and 1984, came to a similar conclusion: in the course of the life of a typical Swede, starting school later translated to reduced over-all earnings. In a 2008 study at Harvard University, researchers found that, within the U.S., increased rates of redshirting were leading to equally worrisome patterns. The delayed age of entry, the authors argued, resulted in academic stagnation: it decreased completion rates for both high-school and college students, increased the gender gap in graduation rates (men fell behind women), and intensified socioeconomic differences.

As it turns out, the benefits of being older and more mature may not be as important as the benefits of being younger than your classmates. In 2007, the economists Elizabeth Cascio and Diane Whitmore Schanzenbach decided to analyze the data of Tennessee’s Project STAR—an experiment originally designed to test the effects of classroom size on learning—with a different set of considerations: How would the relative class composition affect student performance? Their approach differed from most studies of redshirting in one crucial way: the students had been assigned totally randomly to their kindergarten classrooms, with no option for parents to lobby for, say, a different teacher, a different school, or a class in which the child would have some other perceived or actual relative advantage. This led to true experimental variation in relative age and maturity. That is, the same student could be relatively younger in one class, but relatively older in another, depending on his initial class assignment. The researchers discovered that relatively more mature students didn’t have an academic edge; instead, when they looked at their progress at the end of kindergarten, and, later, when they reached middle school, they were worse off in multiple respects. Not only did they score significantly lower on achievement tests—both in kindergarten and middle school—they were also more likely to have been kept back a year by the time they reached middle school, and were less likely to take college-entrance exams. The less mature students, on the other hand, experienced positive effects from being in a relatively more mature environment: in striving to catch up with their peers, they ended up surpassing them.

Cascio and Schanzenbach’s results point to a logic that proponents of mixed, or split-grade, classrooms have long espoused: younger students benefit from having older peers. As long as the relative classroom composition isn’t too skewed in the younger direction, researchers have found no negative effects from combining the earliest school grades—kindergarten and first grade, or first and second grade—on the students. In fact, they’ve discovered quite the opposite: in 2011, a group of Norwegian economists concluded that mixed grades resulted in an over-all positive effect—mixed-grade students outperformed those in standard, single-grade classes on both classroom and standardized tests, largely as a result of the benefit that younger students derived from being among older ones. The older ones, on the other hand, suffered as a result of the mixing, but not enough to offset the gains of the younger students.

Few researchers would dispute that, in the immediate term, being relatively bigger, quicker, smarter, and stronger is a good thing. Repeatedly, the studies have found exactly that—older kindergarten students perform better on tests, receive better teacher evaluations, and do better socially. But then, something happens: after that early boost, their performance takes a nosedive. By the time they get to eighth grade, any disparity has largely evened out—and, by college, younger students repeatedly outperform older ones in any given year.

Why would that be the case? It all comes back to that relative difference: if you are always bigger and smarter, you may be more likely to get bored, and to think that everything—learning included—should come easily. You don’t have to strive and overcome obstacles in the form of older, more developed kids. If, on the other hand, you’re on the younger end of the spectrum, you are constantly forced to reach for your limits. And unlike in sports, where physical size often plays an undeniable, difficult-to-circumvent role in your eventual success, in school a physical disadvantage can turn into an academic advantage: children may learn to compete where they can succeed, where their persistence and attention can accomplish what their physical size may not.

These skills translate to a mindset that is crucial to lifelong achievement. In a way, the choice between redshirting and not is the choice between providing your child with a maturity boost or a challenge. While there is certainly an absolute benefit to being bigger and stronger, learning to deal with and overcome obstacles also has a long-lasting effect. It’s a quality the psychologist Angela Duckworth calls “grit,” and Carol Dweck dubs the “incremental mindset”: the knowledge that perseverance, dedication, and motivation can help you where an absolute advantage may not immediately come to the rescue. If you’ve always been praised as the best and brightest, chances are that that self-perception will eventually backfire; if you’ve had to earn your distinctions, they’re more likely to last.

Friedman’s son was born on time—one day late, in fact—rendering any decision on redshirting largely irrelevant. He is now twenty months old. Last week, he started pre-school. “He will be the youngest,” Friedman said. “At this stage, we want to socialize him and have him look up to other kids’ skill sets.” Why the change of heart? Her original logic, it turns out, was based on her own research into the role of relative age on sports performance and sports-related injuries. But when she stopped to consider the literature on academics—along with the real-life example of her husband, born in July—she realized that, at least in that respect, the logic no longer applied. Younger could be better after all.

Maria Konnikova is the author of the New York Times best-seller “Mastermind: How to Think Like Sherlock Holmes.” She has a Ph.D. in psychology from Columbia University.

Photograph by Astrid Riecken for The Washington Post via Getty.