In the past, the perception was that all-girl schools focused mainly on proper etiquette. But times have changed and so have the schools, weakness into a strength. Educators say an all-girl atmosphere keeps the focus on academics for students like 17-year-old senior Erica Chan. Chan is editor of the yearbook, an athlete in 3 sports, and plans to pursue a career in medicine. According to the National Coalition of Girls' Schools, enrollment at their member schools has increased by almost 30% in the last 10 years. David Satker, who's written extensively on a subject, says all-girl classes can boost self-esteem and allow girls to thrive in subject like math and science, areas historically dominated by males. As for Erica Chan, after 13 years at an all-girl school, next fall she's headed to a co-ed college for a whole new experience, but she'll go with the confidence she feels she would not have developed at a co-ed school. Elaine Kihano, CNN Baltimore.