The school year begins, and yet another private, all-boy high school, St. John's, announces it will be forced to open its enrollment to girls in order to survive financially. Declining enrollment at private schools in the District and surrounding area mirrors the declining enrollment in District public schools. A shrinking high-school-aged population forces mergers between boys' and girls' high schools or the opening of enrollment in boys' schools in order for the schools to survive.

Unfortunately, there are some real losers in this enrollment opening and school merging. The losers are the young women who would normally choose an all-girl school or be sent to an all-girl school by their parents.

Separating boys from girls is a real plus at the high school level. Research studies clearly show that women, in particular, benefit from the educational process in a single-sex school. There are far fewer distractions and students tend to develop better comraderie with other students and with their teachers in all-boy or all-girl schools.

Conversely, in a coeducational high school there are many distractions and peer pressure by both boys and girls to "be cool" for the opposite sex. Boys will be the losers when their school becomes co-ed. Parents of female students, who will help choose a school for which they are willing to pay for quality education, will be well advised to ignore the siren call for a co-ed school. Their daughters will be better served by the learning experiences offered by an all-girl school. EDWARD T. BARRON Washington