It was a sunny fall day, the kind of day your mom insists you spend outside, running around, laughing and making noise. But for 30 girls, in grades one to eight, it was a day for concentration, strategy and competition.

The Washington-area kids competed in the U.S. Chess Center’s first all-girls chess tournament last month. The day included four rounds of games. Each girl had 30 minutes per game to make her moves.

The girls sat quietly, stared at the boards and scribbled down their moves to study later. Naomi Miller, a sixth-grader at Springfield Estates Elementary School in Springfield, Va., won two matches, drew one (meaning it was a tie) and lost one.

“There really are so many new things to learn,” she said. “I don’t think it matters if I’ve lost or not. I like thinking back and seeing if I could have made another move.”

This was Naomi’s second chess tournament and her first all-girls matchup. This one, she said, “was way more casual.” When a boy opponent says to her at the beginning of a match, “Are you ready to play?” Naomi feels as though what he is really saying is, “Are you ready to lose?”

This kind of attitude is in part why the U.S. Chess Center decided to host an all-girls event. At most youth chess tournaments, according to Chris Kim, the tournament director, only about 5 percent of players are girls. That means, out of 100 players, only five of them are girls. That’s a lot of boys.

“Most girls feel intimidated,” Kim said, as his daughters, Madeline and Charlotte Kim, battled it out over the chess board. Girls may pick up the game in elementary school, but as they get older, they stop playing because of peer pressure. “My daughters’ main complaint was, ‘How come we always have to play boys?'”

Pallavi Bhave, a fifth-grader at Westminster School in Annandale, Va., plays on her school chess team, which has seven girls and 36 boys. “Most of my other friends do chorus,” she said, “I think chess is better because you actually think and it helps you concentrate.”

Joie Wang, a sixth-grader from Greenbriar West Elementary School in Fairfax, Va., tied with Madeline for first place in the senior division (grades five to eight). Sarah Slate, a fourth-grader at Hunters Woods Elementary School in Reston, Va., and Mahati Malladi, a fourth-grader at Greenbriar West, tied for first in the junior division (grades one to four).

Joie has competed in dozens of tournaments in the three years she has been playing. When asked why she plays chess, she said simply, “I like how I beat people.”