The advantages of single sex education for boys aren't as clearly defined by research as the advantages for girls, but there are definitely advantages to all boy classrooms. Most people who have seen coed classrooms in elementary school are likely to notice that the boys are more active and more frequently redirected by the teacher. That's because boys and girls may learn better when they are taught in a more gender-specific manner.
That's not to say that all children of one gender learn in the same way--in fact the National Association for Single Sex Public Education is clear in pointing out that the position is not that "all girls learn one way and all boys learn another way," but that there are differences in the way boys and girls learn, and that acknowledging that in the classroom is advantageous to both girls and boys.
The Advantages of Single Sex Education for Boys
1. The ability to be taught in a style more conducive to boys' learning. Although many experts and parents downplay it, boys and girls do learn differently. In the book "The Minds of Boys: Saving Our Sons from Falling Behind in Life and School," co-authors Michael Gurian and Kathy Stevens outline a number of differences between the brains of girls and boys, differences that have a direct effect on how boys learn. Among their findings are that boys tend to compartmentalize brain activity, meaning they are more successful in learning when they are focused on one activity for a long time as opposed to moving from one activity to the next.
The part of boys' brains that processes language develops less quickly than girls, making them more likely to achieve in a classroom full of diagrams and visual aids then from a teacher who spends a lot of time talking. More importantly, the male brain tends to enter a sort of resting state between tasks. If teachers in single sex classrooms take this into account, boys look less like they're not paying attention and more like they're preparing to get on to the next learning task.
2. The ability to gain a more well-rounded education. Coed classrooms and schools make it hard for boys to explore all subjects fully, for fear of being a geek or not looking macho enough to the girls. With single sex education, some of that competition and stereotyped gender roles are removed, making it more acceptable for boys to read, write and explore the fine arts.
3. The chance to have their sensitive sides nurtured. We know that girls are sensitive, but boys are too. In the typical coed classroom, teachers are often careful in making sure that girls' feelings aren't hurt and that they have the opportunity to express their emotions. This is not always true for boys, who need to express feelings but often do so in a less verbal manner than girls.
In a single sex classroom, teachers with appropriate training can help boys access and express these emotions. Gurian and Stevens suggest that while talking is important, the way in which you do so is also important. Instead of sit-down conversations, boys do better with conversations on the move or "talking while walking."