An already heated debate over single-sex education is boiling over. Many public schools have been experimenting with putting boys and girls in separate classrooms for part of the day, or using single-sex academies as a low-cost way to try and raise academic performance. But a new study published in Science magazine finds no solid evidence that such methods work — and offers evidence that single-sex education is more likely to make children sexist, by increasing gender stereotyping and legitimizing institutional sexism. Are boys- and girls-only classrooms counter-productive?

Apparently. We should not be teaching kids sexism: Nobody is saying children learn less in sex-segregated classrooms, says Madeline Holler at Babble, but they're not learning more that way either. And now we find out it "makes kids sexist"? It's pretty clear that our "desperate effort to raise test scores and improve education" is not working as promised.
"Single-sex schools don't work and they make kids sexist"

Come on. This study is bogus: Plenty of studies have already suggested that girls do worse when outnumbered by boys in the classroom, says Hank Campbell at Science 2.0. These psychologists are simply dismissing that body of evidence, and then supporting their claim of sexism by citing a mere "few weeks watching preschoolers." It sounds like they're basing their argument "on philosophical rather than scientific grounds."
"Are single-sex schools better for education"

The truth is we're not sure: The evidence supporting same-sex schooling isn't exactly conclusive, says Paul E. Peterson at Education Next. But there's certainly no proof it's less effective than co-ed classrooms. Teachers and many parents favor the idea by a 2-to-1 margin. So if nobody's sure, "why not let parents choose which type of schooling is best for their child?"
"Public wants single-sex school option, even though professors do not"