Plato used to teach both boys and girls in the same class, insisting that there was no difference between the intellectual capability of the sexes, but somehow society regressed into the oppression of women, and women were not allowed to go to school at all in certain parts of the world. After World War II, more and more women started to go to school with boys because there were so many other issues at hand that this was no longer refuted. The number of single-sex state schools in the U.K., for example, has fallen from around 2,500 to a little over 400 in the last four decades. This shift in women's education has helped liberate women, giving them opportunities they didn't have before. Before this change, boys would have different classes than girls. Boys would study politics and war while girls would study home economics. Educating boys and girls in the same class changed the existing hierarchy of labor.
Another advantage of coeducation is that there is increased competition in the classroom - between girls and boys. Some say this causes girls to perform better than boys. Others, such as staff at the Cathedral School in the U.K., say that both boys and girls attain the same percentage of A grades, "indicating that neither gender is disadvantaged by the other" and that "in fact, the reverse is true, both are enhanced by the presence of the other." This is in contrast to the early beliefs about coeducation, when people were against it because they thought coeducation would be detrimental for girls, who would be harmed by "overexertion caused by competition with male students."
Being in a coeducation school can be beneficial for both girls and boys by training them to develop into their roles naturally in the real world, where men and women must live and work alongside each other. Being together in the same classroom helps break down stereotypes for each sex about the other. This interaction with the opposite sex from an early age challenges sexist attitudes later in life.
A disadvantage of coeducation schools is that sometimes, boys and girls both get distracted by the other sex. Some parents object to the idea of coeducation on religious and moral grounds, insisting that promiscuity is raised in coeducation environments.