From the Washington Post, by Danial Willingham
The idea that students would learn better in single-sex classrooms seems logical. The typical arguments include:
- Boys find girls more distracting in class than they find other boys. Likewise, girls find boys more distracting.
- Sex differences in math and science achievement are a product of
social influence. Those influences will be reduced or eliminated if
girls are in classrooms only with girls.
- Boys dominate classroom discussion, and so girls are denied practice in articulating and defending their views.
- Boys and girls have different brains, and therefore learn
differently. If they are taught separately, teachers can tune their
instruction to the way each sex learns.
The last of these is frequently overwrought and over-interpreted, but
generally, these reasons seem plausible. But that obviously doesn’t
prove that single-sex education confers any advantage to students.
A 2005 report written for the Department of Education (Mael et al, 2005)
reported mixed effects, but generally a positive conclusion for
single-sex classrooms in short-run academic outcomes. There was no
indication of a boost to longer-term outcomes.
A new study (Pahlke, Hyde, & Allison, 2014)
reports a meta-analysis of 184 studies representing 1.6 million
students in K-12 across 21 nations. The authors place considerable
emphasis on the problem of control in this research. They end up
concluding that, with proper controls, analyses show that single-sex
classrooms don’t help students much.
The challenge in this sort of work is that comparisons of single-sex
and coed classrooms often do not use random assignment. Students (or
parents) choose a single-sex classroom. So for this review, the authors distinguished between controlled experiments
(the original study either used random assignment or made some attempt
to measure and statistically account for associated variables) and
In controlled studies, there were statistically reliably, but
numerically quite modest positive effects of single-sex classrooms for
both boys and girls in mathematics achievement, science achievement, and
verbal achievement (Hedges g in all cases less than 0.10).
Girls showed an edge in single-sex classes for math attitude, science
achievement, and overall academic achievement, but again, the gains were
modest. If one restricts the analysis to U.S. students, virtually all
of these small effects disappear.
There was no effect for attitudes towards school, gender
stereotyping, educational aspirations, self-concept, interpersonal
relationships, or body image.
There were not enough controlled studies to examine aggression, body
image, interpersonal relations, interest in STEM careers, science
attitudes, or victimization.
It’s also notable that there was no dosage effect: the advantage was
no larger when all classes within a school were single-sex classes,
compared to when a single class was.
The authors were also interested in evaluating whether single sex
classes were effective for boys of color.
They reported that there were
not enough controlled studies to answer this question, but even
restricting the analysis to uncontrolled studies, the effects were
When you consider the factors that we know contribute
substantially to academic attitudes and performance–the student’s prior
academic achievement, the curriculum, the home environment, the
teacher’s skill–it’s easy to believe that the sex of the other students
would have a modest effect, if any.
That said, it could be that a single sex school has a profound
influence on a few students. A few years ago, friends of mine moved
their 15 year old daughter to an all-girls school because she was “boy
crazy.” According to my friends, she didn’t become any less interested
in boys, but she did focus on work better during school hours. But then
again it’s possible my friends were kidding themselves.