The number of schools trying single-sex education is growing, according to an article published by the Associated Press. Since the U.S. Department of Education relaxed restrictions on schools separating classrooms by sex in 2006, the number of single-sex classrooms around the country has slowly multiplied. In 2002, only about a dozen public schools offered single-sex instruction. Now, nearly 500 schools offer at least some all-boys or all-girls classroom options.

Middleton Heights Elementary School became the first in Idaho to split the sexes into different classes. The school’s principal Robin Gilbert said that although boys and girls are covering the same curriculum, it became apparent to her that they prefer a different learning environment. In the school, boys and girls still meet during lunch period and recess, but when the bell rings, they go to different rooms. The boys have a blue chalkboard and walls covered with fishing and camping pictures, while girls cover their walls with red paper hearts.

Gilbert says that the quality of instruction offered to both types of classroom is identical, but the American Civil Liberties Union, which has sent a public records request relating to the sex-separation program to Middleton Heights as part of its recently launched Teach Kids, Not Stereotypes program, disagrees. In addition to Middleton Heights, the ACLU also requested records from school in another five states and sent cease-and-desist letters to schools in Maine, Alabama, Mississippi, Virginia and West Virginia.

Recently, the ACLU successfully challenged single-sex programs in the Adrian R-III school district in Missouri and applied enough pressure to have similar plans dropped from schools in Louisiana. Gilbert, however, seems determined not to cave.

“It doesn’t frustrate me,” Gilbert said of the criticism, “but it makes the work harder.”

The opponents of single-sex education are relying on findings such as those of a recent survey of studies looking at benefits of separating the sexes in the classroom published by Science magazine. Diane F. Halpern, the author and a former president of the American Psychological Association, said that the findings don’t support the contention that single-sex instruction is beneficial. She also says that single-sex classrooms are more, rather than less, likely to promote gender stereotypes.

However, proponents have put out their own studies, showing the benefits of separating students. Middleton Heights Elementary cited the research when it first piloted single-sex classes in a few grades. The goal was to address the struggles boys were having in reading.

The idea proved so popular that single-sex classes have expanded throughout the school. Parents can opt out, a choice required by law, if they want their kids in a traditional coed classroom.