Has your local public school opened up a new all-girls classroom? Are you tempted to enroll your daughter in it? After all, the principal may have offered up impressive evidence that girls learn in very different ways from boys, and this segregated classroom seems to be a great boon to girls.

The idea that the brains of girls and boys are so different that they should be parented and educated in different ways and steered towards very different careers is one of the most successfully promoted media narratives of the decade.

A small group of advocates have pushed this notion so hard that it’s become the conventional wisdom. They write best-selling books, speak to large groups of teachers, parents and school administrators, and are quoted—endlessly and usually uncritically–by the news media. They claim that due to vast differences between boys and girls, the single sex classroom will improve children’s academic achievement. That’s the argument made by Leonard Sax, head of the National Association for Single Sex Public Education and best-selling author of Why Gender Matters, and Michael Gurian (The Wonder of Girls).

They’ve been very successful. The New York Times reports that,

There were only two single-sex public schools in the mid-1990s; today, there are more than 500 public schools in 40 states that offer some single-sex academic classes or, more rarely, are entirely single sex.

But don’t drink the Kool Aid. Much of what we are being told today about single-sex classrooms is junk science, a great deal of it of it actually harmful to girls. These “boy-girl” classrooms are being set up on the basis of science that is outdated, incomplete or just plain wrong.

For example, while “boy” classrooms are active and rowdy, “girl” classrooms are quiet and subdued, and children are encouraged to sit close to teachers and to speak in soft voices. In South Carolina, teachers in all-girls classes say they have learned to speak more softly, because their students can take yelling more personally than boys.

The quiet classroom is based on the “fact” that girls hear better than boys. In Why Gender Matters, Leonard Sax claims that girls hear 10 times better than boys. “If a male teacher speaks in a tone of voice that seems normal to him, a girl in the front row may feel that he is yelling at her.”

But do girls in fact hear better? No. Mark Liberman, a linguistics professor at the University of Pennsylvania, says that Sax misrepresented the studies he examined to make that claim. In reality, “There is no functionally significant difference between boys and girls in auditory sensitivity.”

In many single sex-classrooms, gender becomes the center of the curriculum. And the educators assign action novels for boys to read or allow girls to evaluate cosmetics for science projects. In classrooms in Mobile, teachers encourage kids to use highly gendered words in writing assignments. According to one school,

[A] writing prompt for a boy might be what place in the world he would most like to go hunting or to drive on a racetrack, while girls might write about their dream wedding dress or their perfect birthday party.

In 2009 the Today show profiled a single-sex school located in suburban St. Louis, and the reading materials for the two sexes were quite different. Boys read stories featuring monsters while girls read stories featuring movie stars.

Such classes are based on the notion that the very different brains of boys and girls motivate them in very different ways—with girls interested in relationships and fashion and boys interested in sports, combat and building things.

But there is no such data. Recent research finds the differences between girls’ and boys’ brains are trivial.

Lise Eliot, Associate Professor in the Department of Neuroscience at the Chicago Medical School, did an exhaustive review of the scientific literature on human brains from birth to adolescence and concluded, in her book, Pink Brain, Blue Brain, there is “surprisingly little solid evidence of sex differences in children’s brains.”

Rebecca Jordan-Young, a sociomedical scientist and professor at Barnard College, also rejects the notion that there are pink and blue brains, and that the differing organization of female and male brains is the key to behavior. In her book Brain Storm: The Flaws in the Science of Sex Differences, she says that his narrative misunderstands the complexities of biology and the dynamic nature of brain development.

Nonetheless, a major tenant of the segregated classroom is the idea that boys naturally relate to objects and understanding systems and math and science, while girls gravitate towards relationships and caring. Girls are not natural leaders or risk takers, and don’t take naturally to math, it’s argued.

British psychologist Simon Baron-Cohen claims that the “male brain” is the “systematizing brain” while the “female brain” is the “empathizing brain.” (Though Baron-Cohen says that women can have “male brains” and men “female brains,” he makes clear that “on average, more males have systematizing brains while more females have empathizing brains.”) He has been published in the New York Times, quoted in a Newsweek cover story, and featured in a PBS documentary and in countless other major media outlets.

This idea was based on a study of day-old babies which found that the boys looked at mobiles longer and the girls looked at faces longer. “Male brains,” Baron Cohen says, are ideally suited for leadership and power. They are hard-wired for mastery of hunting and tracking, trading, achieving and maintaining power, gaining expertise, tolerating solitude, using aggression and taking on leadership roles.

And what of the “female brain?” It is specialized for making friends, mothering, gossip, and “reading” a partner. Girls and women are so focused on others that they have little interest in figuring out how the world works.

Is this true? No. Baron-Cohen’s study had major problems. It was an “outlier” study. No one else has replicated these findings, including Baron-Cohen himself. It is so flawed as to be almost meaningless. Why?

The experiment lacked crucial controls against experimenter bias and was badly designed. Female and male infants were propped up in a parent’s lap and shown, side by side, an active person or an inanimate object. Since newborns can’t hold their heads up independently, their visual preferences could well have been determined by the way their parents held them.

There’s little evidence for the idea of a male brain hardwired to be good at understanding the world and a female brain hardwired to understand people. There is a long line of literature flat-out contradicting Baron-Cohen’s study, providing evidence that male and female infants tend to respond equally to people and objects, notes [PDF] Elizabeth Spelke of Harvard University’s Laboratory for Developmental Studies. But media stories continue to promote the idea of very different brains.

As for the idea of girls “naturally” turning to dolls and avoiding blocks, Jordan-Young points out that girls do not shun toys that involve building things. In one Swedish study [PDF], she reports, Lincoln Logs turned out the favorite toy of all the girls. Girls played with those by a 6 to 1 ratio over some other toys, and girls also spent three times longer playing with toy cars and a garage than they did with a baby doll.

Another problem with single sex education is that boy classrooms are set up for action, while girls are expected to sit quietly while learning.

The Today segment in St. Louis begins with a video showing boys engaging in calisthenics and girls sitting quietly at their desks reading and writing. Boys were permitted to learn anywhere in the classroom: under their desks, in tents, or standing on chairs. No similar alternative learning opportunities were provided for girls.

But in fact, research finds that physical activity helps both boys and girls learn. Professor Charles Hillman of the University Illinois at Urbana-Champaign has found that aerobic fitness is related to better performance on school-based achievement tests of mathematics and reading.

We asked Dr. Hillman if there were any gender differences in his findings. He said there were not:

We have never found sex differences in our work. We have included sex as a variable to investigate this question and never found support for it.

Yet assuming gender differences, as same-sex classrooms do, can actually create those differences. Too often, even girls with an early interest in math are discouraged by adults who have bought into the idea that girls don’t have a natural aptitude for math and science. In one study,

[P]arents perception of their children’s competence in mathematics have been found to be influenced by their children’s gender, independent of the children’s actual performance in mathematics.



The idea of an innate “girl brain” not suited for math has been the cause of a “leaky pipeline” in which girls are lost to math and science all through their school years. Between fourth and twelfth grades, the percentage of girls who say they like science decreases from 66 to 48 percent. In those same years, the percentage of girls who say they would prefer not to study math any more goes from 9 percent to a whopping 50 percent [PDF].

But the tide may be turning. The notion of classrooms tailored to boy or girl brains is taking some serious flak. In September, the journal Science published an article by eight prominent scientists, titled “The Pseudoscience of Single-Sex Schooling.” They argue,

There is no well-designed research showing that single-sex (SS) education improves students’ academic performance, but there is evidence that sex segregation increases gender stereotyping and legitimizes institutional sexism.

The lead author on the piece was Professor Diane Halpern of Claremont McKenna College, past president of the American Psychological Association.

The authors of the Science article are calling on president Obama to rescind changes made under the Bush administration that watered down provisions of the Title IX rules against unequal resources in education to allow more public single-sex classrooms. Given the fact that there is little to no evidence that single-sex classrooms in public schools improve academic achievement, such a move makes sense. And, the authors add, “Funds spent on training teachers in nonexistent ‘gender-specific learning styles’ could be better spent on training them to teach science, mathematics, and reading, or to integrate boys and girls more completely in the learning environment.”

The girly classroom, filled with quiet children who don’t move much, who are encouraged to write about wedding dresses and never build anything, is based on a fundamental misunderstanding of actual research.

It’s time to consign it to the dustbin of history.

Caryl Rivers, a Boston University journalism professor, and Rosalind C. Barnett, senior scientist at the Brandeis Women’s Studies Research Center are the co-authors of The Truth About Girls and Boys: Challenging Toxic Stereotypes About Our Children.