Are Single-Schools Or Coed Schools Better For Kids? Scientists Don’t Know.

Should you enroll your kids in coed schools, or splurge on single-sex private schools? It’s a tricky decision made trickier by the fact that conventional wisdom is often at odds with data. If girls in coed schools are distracted and shouted down by boys why do they perform so well? If boys in single-sex parochial schools are given more time to mature why aren’t they more successful in high education? The truth is that no one exactly knows. The data on coed versus single-sex education can be read to support just about any argument.

But if every argument can be supported, none can be made without caveats. Sure, there are physical differences between male and female brains, but who says that affects how children learn? For every study that shows single-sex schools increase the risk of children ascribing to gender stereotypes, there’s a study that shows gender stereotypes plummeting in single-sex schools. And don’t even get us started on long-term academic outcomes. A strong case can be made that graduates of single-sex versus coed schools are more, less, and equally intelligent.

Here’s a look at the data, which is no less fascinating for being profoundly inconclusive.

Boys And Girls Have Different Brains—But Who Cares?

There are obvious differences between the physical structures of male and female brains. Men have more cerebral volume—a measure of brain size—than women, and cerebral volume peaks at about 10 years in females and 14 years in males, as seen in the data below. The sexes may even process language differently—studies suggest the language regions of a three-year-old girl’s brain look similar to that of a five-year-old boy. Some experts suspect that these brain differences may have implications for kids who develop differently but are confined to coed classrooms. “It’s not enough to teach well,” Leonard Sax, author, psychologist, and director of the National Association for Single Sex Public Education, told the American Psychological Association in 2011. “You have to teach well to kids who are developmentally ripe for learning.”

At the same time, other experts are far from convinced that these differences have any implications in the classroom. Besides, brain size is a notoriously bad way to measure intellect. Almost all large mammals have bigger brains than humans and, even when one controls for size by establishing a body-to-brain mass ratio, humans fall somewhere in the middle, as seen in the data below. Our kids are probably smarter than frogs and mice—so how much stock should we put in brain morphology when trying to decide whether our kids should be in single-sex schools?

Single-Sex Schools Make Kids Sexist—Except When They Don’t

One of the main purported advantages to single-sex schools is that children feel less pigeonholed into gender roles. In an all-women classroom, for instance, young women aren’t obliged to avoid science and invest in the arts to please their male peers. Indeed the data below, culled from a 2007 APA study, demonstrates that women and men who attend single-sex high schools are less likely to pick majors in college that are traditionally associated with their sexes.

But that’s far from the final word on how single-sex schools impact gender stereotypes. For instance, one 2010 study in Child Development evaluated 57 preschoolers who were separated by sex for two weeks. Teachers were asked to use gendered language, and have boys and girls present their work separately, by sex. As the data below illustrates, the researchers found that just two weeks of what they called “high salience” sex division was enough to cause toddlers to ascribe to gender stereotypes and become less interested in playing with the opposite sex. In other words, kids are going to be exposed to stereotypes regardless of what school they attend.

Kids In Single-Sex Schools Are Smarter—Or Not

Whether kids enrolled in single-sex schools perform better academically than those enrolled in coed schools is a scientific toss-up. There are literally hundreds of studies in both directions. We chose two of them, which drive home the difficulty of solving this scientific conundrum.

The first visualization below comes from a fascinating 2013 study, which exploited a South Korean law that randomly assigns students to either single-sex or coed schools. Which means the hard work was done for them—all they had to do was track each student’s progress and see how both sets of randomly-assigned students turned out. They found that those attending single-sex schools performed better on standardized tests, were more likely to attend a four-year college, and less likely to junior college (a negative academic outcome). The effects were strong for both boys and girls, but across most metrics the boys saw the greatest benefits.

And yet observe the subsequent data, taken from an incredibly thorough meta-analysis conducted in 2014. Sure, many studies included in the meta-analysis found that kids in single-sex schools had higher levels of academic achievement. But none of them came even close to statistical significance—suggesting that these blips are no reflective of a trend. In a word, students at single-sex and coed schools performed about the same, statistically speaking.