The National Association for Single Sex Public Education cites several studies that show higher test scores as one positive effect of gender-separated schools for boys. In one, a four-year study by Stetson University of fourth grade students at Woodward Elementary, 85 percent of boys in single sex classes scored 'proficient' on the Florida Comprehensive Assessment Test, compared to only 55 percent of boys in coed classes, even with the same curriculum, demographics and class size. Andersen Junior High School, in Arizona, saw similar results in seventh and eighth graders.
Proponents of single sex classrooms claim that another positive effect is having a learning environment that is tailored to boys, and therefore, is more effective. In general, boys are usually more competitive than girls, have more energy, are more visual and do not have the same listening skills as girls. In a single-sex classroom, teachers can use instructional methods that tap into the natural tendencies of boys, such as allowing physical movement during lessons, a practice that as of 2010 was done in Anderson Junior High, according to the Arizona Republic. Boys-only classes eliminate the distraction of worrying about the opposite sex in the classroom or being embarrassed to answer a question in front of the girls.
Unfortunately, separating classes can have unintended negative effects. An article from the Washington Post claims that research shows that labeling and segregating children by gender in schools increases stereotyping and prejudice, in a way similar to separating classes by race. Placing students in classrooms based purely on their gender teaches children that boys and girls "have different types of intellects, and reinforces sexism in schools and the culture at large."
The Washington Post article also points out that children who spend most of their time with peers of the same gender lack diversity in their interests and skills. They claim that boys who spend most of their time with other boys become more aggressive and more "one-dimensional" when compared to their peers who spend time with both genders. A mix of both masculine and feminine interests has been linked to better mental health. In separated classes, boys lose the chance to work with and learn from girls, which is an important skill for the future workplace.