Public education practices should be based on research, not nursery rhymes. But a bill that would allow public schools to experiment with single-sex classrooms has no more basis than the old doggerel that tells us what little girls are made of.

The bill was sponsored by Sen. John Tuttle, D-Sanford, on behalf of his local school district, which shut down its optional single-sex program for sixth-graders after getting a complaint from the American Civil Liberties Union.

The school district had tried the program for several years and felt it could show good results. Tuttle’s bill would give Sanford and other districts a chance to try to see whether kids learn better when the boys and girls are sitting in separate classrooms.

In a 2011 study in the journal Science, “The Pseudoscience of Single-Sex Schooling,” researchers found little basis in the literature to support that experiment.

Although it’s easy to observe differences between boys and girls in the classroom, very few of these differences can be observed in objective studies by brain scientists.

The differences are cultural, which is why separating boys and girls at a young age is dangerous.

The schools won’t fix cultural gender stereotypes by separating children; they are more likely to reinforce them. If both boys and girls are told that girls are too shy to raise their hands in a mixed-gender classroom, so they have to be sent to a quieter place where they can learn, they will carry that message through life.

Boys who don’t see girls performing alongside them in the classroom will develop ideas about girls’ abilities based on what others tell them. They won’t grow up seeing girls as individuals and knowing some who fit the stereotype and others who do not. Girls won’t see boys who are quiet and thoughtful; they’ll assume that they’re all like the cartoon image that single-sex education advocates draw of boys who need constant physical action.

These are not lessons that schools, especially public schools, should be teaching to children. In a world in which men and women have to work together and respect each other, these are the wrong messages to send.

It is possible to create a single-sex environment that does not perpetuate gender bias, but it should be done with great care and it should be based on reliable research. A gut feeling that it might be a good idea is not enough.

Little girls are not made from sugar and spice. They are made from the same stuff as boys, and that’s what schools should teach.