ENCINITAS, Calif. - Public school yoga instructor Katie Campbell proudly looks out at 23 first graders as they contain their squirming in a kid-friendly version of the lotus position.
In a voice barely above a whisper, she says into her microphone: "Why look at everyone showing me they're ready for yoga. A-plus, plus, plus!"
Then the lesson begins with deep breathing and stretches common to many yoga classes. There is no chanting of "om," no words spoken in the Indian language of Sanskrit, nor talk of "mindfulness" or clasping hands in a prayer position.
Campbell avoids those potential pitfalls for the Encinitas Union School District, which is facing the threat of a lawsuit as it launches what is believed to be the country's most comprehensive yoga program for a public school system.
Parents opposed to the program say the classes will indoctrinate children in Eastern religion and are not just for exercise.
It's a debate public schools across the country are increasingly facing with the rising popularity of the practice and the recent dispute over school prayer.
Yoga is taught at public schools from rural West Virginia to bustling Brooklyn as a way to ease stress. But most classes are part of an after-school program, or are offered only at a few schools or by some teachers in a district.
Encinitas is believed to be the only public school system that will have yoga instructors teach full time at its nine schools as part of an overall wellness curriculum that includes nutrition and a school garden program, among other things.
"This is 21st-century P.E. for our schools," said Superintendent Timothy Baird. "It's physical ... but it also deals with stress reduction and focusing, which kickball doesn't do."
The program is expected to teach a 30-minute yoga lesson to 5,000 students twice a week at district schools, which run kindergarten through sixth grade. It is funded with a $533,000 grant from the Jois Foundation, a nonprofit whose board of directors includes the son of the late Indian instructor Krishna Pattabhi Jois, whose teachings are said to have popularized Ashtanga yoga in the Western world.
Jois Foundation's program director Russell Case said Encinitas is building a national yoga model for public schools.
Researchers at the University of Virginia and University of San Diego will study the program, including analyzing data on students' resting heart rates.
They want to know if public schools can affect not only children's learning but instill in them good eating habits and skills to help their well-being.
The program started in several schools in September but will go district-wide in January after months of protests by a group of parents.
Mary Eady pulled her first-grade son out of the classes.
Eady said she observed a kindergarten class in which the children did the motions referred to in yoga practices as a sun salutation. The folded over children, stood upright, sweeping up their arms toward the sky.
She said while the teacher called it an "opening sequence," the connotation was the same in her mind: Students were learning to worship the sun, which went against her Christian beliefs that only God should be worshipped.
"It will change the way you think," she said. "What they are teaching is inherently spiritual, it's just inappropriate therefore in our public schools."
Attorney Dean Broyles says they are considering suing to halt the program.
Despite the long debate over prayer in school, constitutional law experts say the courts still have not clearly defined what constitutes religion.
Encinitas Assistant Superintendent David Miyashiro said administrators were not taking any risks.