For an increasing number of public schools, the formula for a better education requires a little arithmetic: separate the girls from the boys.
That is just fine with Kristielle Pedraza, a 13-year-old who says she will not miss the boys while she attends the Irma Rangel Young Women's Leadership School, Dallas's first all-girl public school and one of a growing number of such schools nationally.
"Usually it's the guys that distract all the whole class. They're usually the class clowns," said Kristielle, who just entered the seventh grade. "With no guys in the school, I . . . know we will really get busy without much distraction."
At least 10 single-sex public schools are to open this fall in five states -- Texas, Ohio, Pennsylvania, New York and South Carolina.
Advocates say separating the sexes can improve learning by easing the peer pressure that can lead to misbehavior as well as low self-esteem among girls.
"John Kerry, George W. Bush, his father and Al Gore all went to all-boys schools. We don't think that's a coincidence," said Leonard Sax, a Maryland physician and psychologist who founded a nonprofit group that advocates single-sex public education. "We think single-sex education really empowers girls and boys from very diverse backgrounds to achieve."
Some women's groups and the American Civil Liberties Union say segregation of any kind is wrong.
"We think segregation has historically always resulted in second-class citizens," said Terry O'Neill, a vice president of the National Organization for Women.
The number of U.S. public schools offering single-sex classes jumped from four to 140 in the past eight years, Sax said. At 36 of those schools, at least one grade will have only single-sex classes this year.
Advocates said they expect the number to increase now that the Education Department has announced plans to change its enforcement of the landmark discrimination law Title IX, which bars sex discrimination in schools.
"Many school districts wanted to offer this option, but they feared being sued by interest groups," said Sen. Kay Bailey Hutchison (R-Tex.), who supports an amendment in the No Child Left Behind Act that encourages districts to experiment with single-sex education.
The 126 seventh- and eighth-graders at the Dallas school will take pre-honors classes with a heavy emphasis on math, science and technology courses, which traditionally attract fewer girls than boys.
Sax said separating the sexes allows teachers and administrators to focus on the different ways boys and girls learn. Girls, he said, learn better in quiet classrooms and intimate schools where they are on a first-name basis with their teachers. Boys learn better when teachers challenge them to answer rapid-fire questions and address them by their last names.
Single-sex schools also reduce the pressure to preen for boyfriends or girlfriends, Sax said.
"Single-sex schools, in ways that matter, are much more like the real world. Because unless you are a model or an actress, how you look is not the most important thing in your life," Sax said.
Roy Young, a former defensive back for the Philadelphia Eagles, founded Texas's first all-male public school in Houston four years ago. Today, Pro-Vision Charter School has about 100 students in grades five through eight. It combines aspects of the Boy Scouts, fraternities and the military.
One former student who was enrolled in special education when he came to Pro-Vision in fifth grade is now taking college prep courses at his high school, Young said.
"If you added other dynamics to it, say male-female, I don't know if this kid would've ever" come to us and said, " 'Look, this is the problem I'm having. I can't read,' " Young said.
The new all-girl school in Dallas plans to add a grade every year until it becomes a seventh- through 12th-grade campus.
Kristielle's mother, Amy Pedraza, who has a clerical job with the district, was particularly impressed with the admissions process. Kristielle had to submit her grades and test scores, write an essay and go through an interview.
"She's getting all this experience," Pedraza said. "It's just awesome. I wish I could have been her age and doing the things that she's already doing."