On Friday afternoons, kids at Bolinas-Stinson School spend 30 minutes focusing on their breath, staring into each other’s eyes, playing games like Simon Says and occasionally acting like monkeys. But these and other activities aren’t entertainment; they constitute critical pieces of the new mindfulness curriculum, a 13-week program spearheaded by Principal Elaine Doss.

Mindfulness, instructor Lynn Cheatham explained, means “bringing your mind into the present” and “cultivating one’s ability to choose what to focus your mind on,” as well as learning how to deliberately act rather than react. She distinguished it from meditation because the practice invokes no spiritual or religious message, explaining that mindfulness is “not about anything other than just oneself.” Class activities encourage students to leave the past and the future behind and focus intently on the present.

Most mindfulness research has been conducted on adults, but studies on children, especially those with issues such as anxiety, ADHD and conduct disorder, have shown benefits that include improvement in academics and attention and reduced aggressive behavior, according to a summary of the research compiled by the UCLA Mindful Awareness Research Center.

Ms. Cheatham’s interest in mindfulness practices originated in her time spent at the Spirit Rock Meditation Center in Woodacre in the late 1990s. She led teen mindfulness classes there and later founded and directed a Berkeley-based mindfulness program, the Stepping Stones Project. She also consulted for the Green Gulch Farm Zen Center, in Muir Beach.

Last Friday afternoon, with the kindergarten and first grade class, Ms. Cheatham began—as she began all the classes that day—with Simon Says, a game requiring careful attention. Afterwards, she instructed them to lie on the floor “like starfish” and remain still for 30 seconds, a mighty task for five and six-year-olds. “The earth is holding you,” she told them gently.

Unsurprisingly, the kindergarteners and first graders fidgeted. One girl wiggled her purple-socked feet. Another sucked one thumb and rooted around her belly button with the other. But others lay peacefully in the dimly lit room as Ms. Cheatham used her mellow voice, with the occasional aid of a Tibetan bell, to coax them into focusing on their breath.

Over course of the class, they morphed from starfish to tadpoles to newts to “sleepy monkeys.” Later, the students formed a tight nucleus around a snow globe Ms. Cheatham brought as she told them to pick out a single flake and follow it. “Mine’s falling!” one exclaimed. Though not quite the epitome of calm, they certainly paid attention. One kindergartener, Luis, told this reporter that mindfulness was “really fun” because “you get to calm down when you’re sad.”

Not every student is gung-ho about mindfulness, though. An inquiry about the program drew an extended, communal “Uh,” not quite knowing how to respond, from a group of middle schoolers as they waited for the class to start.

“Mindfulness helps us to not be crazy and stuff, but the way they show it [is silly],” said one sixth grader.

Another sixth grader, whose every nail bore different colors and patterns of stripes and polka dots, said she believed it made the students more “energetic” as opposed to calming them down. Her meaning became apparent in class, as the ripple effect of a giggle or comment was almost instantaneous as Ms. Cheatham led class.

But there were periods of quiet as well. “Simon says think about a time you were happy,” she instructed during one moment of relative silence.

“Now we’re going to have mindfulness of the bell,” she said as she gently tapped the small Tibetan bowl and asked them to breathe in and out. But when she asked them to become starfish, the brouhaha rose as they arranged themselves on the floor. “It’s too cold!” one girl shouted loudly. Others lay silently, although it was unclear whether they did so out of enthusiastic participation or adolescent apathy.

At one point during an eruption of giggles, Ms. Cheatham humored them. “Everybody laugh as hard as your can,” she instructed.

The fourth and fifth graders, Ms. Cheatham’s last class of the day, were almost perfectly mindful, despite being on the cusp of those querulous pre-teen years. Ms. Cheatham described them as “very mindful of their mindful practice.”

“Listen to the bell, to the whole length of the bell,” she said gently at the beginning of class, and the students were absolutely silent. During Simon Says, they waved their arms and walked in circles in quiet unison. As they lay on the ground like starfish during a period of guided breathing—“Let the noises pass through like clouds in the sky,” Ms. Cheatham said—the utter quiet and stillness continued and the faded sounds of playground shouts could be heard.

After the class, Ms. Cheatham asked the kids to share their experiences. One said she felt like “I was always going to be safe.” Others felt sleepy, calm, and dizzy but relaxed. Outside, after class, a group of boys enthusiastically agreed (albeit in the presence of their teacher) that they enjoyed mindfulness and use it in disputes with siblings. One girl, fourth grader Cass, said she often feels like she will “explode” at first from having to be still but eventually relaxes and forgets where she is.

Ms. Doss said she hoped the program would serve as preventive measure for bullying. “Why not teach kids how to de-stress?” she asked, adding that it increased empathy by teaching students to avoid knee-jerk reactions. She said that it was “not a forever program” and that “we [will] just see where we are” at the end of the year.