Until this year, most students at P.S. 84 in Brooklyn probably thought “child’s pose” meant being slumped over at a desk at school.

Because the school doesn’t have a gym, an occasional dance class and trips to a nearby park were students’ only physical activity. Now, the children at the elementary school on Berry Street in Williamsburg are learning positions like downward dog and child’s pose as part of a new program to bring yoga into the classroom.

“You have to remember to be focused and calm,” a yoga instructor, Lisa Feuer, told a class of second-graders on a recent Thursday morning. Sitting around on purple mats wearing socks and street clothes, the class members squirmed around on all fours with their bellies over their heads and practiced taking deep breaths.

“I’m too scared,” a 7-year-old in a yellow tank top, Amanda, squealed as she tried to stretch up into a bridge. She later stepped out of the circle to take a breather because, like several of her classmates, she suffers from asthma.

With fluorescent lights and a green linoleum floor, the third-floor classroom is an unlikely spot for a makeshift yoga studio. But the lack of adequate physical education instruction in the city’s schools and skyrocketing obesity rates has created the need for some alternative measures.

The trio of yoga instructors who run the nonprofit Bent on Learning are determined to help combat obesity and attention deficit disorder problems by using tools from the 5,000-year-old discipline. Yoga involves combining a set of poses with breathing exercises and meditation to try to bring mind, body, and spirit into harmony.

The group formed after the terrorist attacks of September 11, when schools near the World Trade Center were looking for ways to combat stress disorders.

One of the founders, Jennifer Ford, discovered as a schoolteacher that she could keep better control over the students if she got them up and moving.

Now, Bent on Learning is working in more than a dozen schools and its instructors teach about 50 classes a week to 1,000 students in schools and youth centers in Manhattan Brooklyn, and the Bronx.

It costs about $7,000 a semester to provide six classes a week of yoga for a school. Bent on Learning raises most of the money through grants and individual donations and recently put out boxes at local yoga studios to help generate funds.

“People don’t want to spend their money on physical education, but they’re shooting themselves in the foot,” one of the founders of the program, Courtney McDowell, said. After years working as a literary agent, she said she got tired of sitting and went to India to study yoga. She later joined up with a former public school teacher, Ms. Ford, and a computer programmer, Anne Desmond.

Ms. McDowell said the practice leads to a “healthier mind and body” and that “putting yourself into awkward positions and then working through it” is an important lesson.

In order to avoid any religious conflicts, many instructors avoid “prayer position,” which involves holding the palms together near the heart. Over the years, a few parents have requested that their children sit out of yoga because they worried that it went against their own religious beliefs.

Most of the students at P.S. 84, which has typically served working class Hispanic families in the neighborhood, had not heard of yoga until they started taking the class this semester.

“It’s really relaxing and calms you down,” a 7-year-old boy, Aaron, who had some trouble keeping still, said. When asked if yoga also made him strong, Aaron flashed a smile and flexed his growing biceps.