By the beginning of the school year next August, none of the classrooms at Vallecito Elementary in San Rafael, California will have chairs.

The school is in the process of becoming the first in the country, and perhaps the world, to shift completely to standing desks. The radical move is based on some basic facts: Many kids are sedentary as much as 80% to 90% of the time they're awake, and over a lifetime, sitting for more than six hours a day increases the risk of death. Standing can increase both fitness and attention spans. If offices are starting to swap out chairs for standing desks, why shouldn't schools do the same?

The program is the brainchild of Vallecito Elementary parents Juliet and Kelly Starrett, who also happen to be co-founders of San Francisco CrossFit, a gym that trains Olympians and other athletes in ultra-intense workouts. After spending a decade lecturing teams and corporations about the hazards of sitting, they realized that their daughter's elementary school had the same problem.

While volunteering at a field day at the school, they noticed that children were struggling to jump in a sack race. Some couldn't even get into the sack at all without sitting down–problems that the Kelly Starrett, a physical therapist, attributes to long inactive days.

"We left that day and that was sort of the first time we thought, hey, we've been recommending standing desks to every adult we work with in the corporate world or athletic world or otherwise, and yet there we are sending our kids off to sit there all day for six hours," Juliet says.

As they did more research, they found increasing evidence of the benefits of standing desks for kids. In a study of hundreds of children in two dozen classrooms in Texas, a researcher from the Texas A&M School of Public Health found that students with standing desks burned 17% more calories than those who were sitting.

For obese kids, the effects are even greater–and the Starretts believe that makes standing desks a perfect intervention for the epidemic of childhood obesity. "Kids with high body mass index can burn upwards of 30% more calories a day standing," says Kelly. "That's childhood obesity wiped out. All you have to do is stand."

The Starretts decided to offer to buy a set of standing desks for one classroom at the school. "I had it in my mind that I was going to have to spend six months and multiple meetings with the principal, and maybe even take it to the district level," Juliet says. "But we sat down and explained five reasons that we thought standing desks would be a good intervention–and in two seconds, she was on board."

Serendipitously, a new fourth grade teacher needed furniture, so she was first to receive the new standing desks last fall. Other teachers liked the idea so much that another three classrooms converted to standing desks over winter break, including a first grade class.

Each classroom also includes some stools so students have the option of sitting, though most quickly shifted to standing. "In the very first class we had fitted, for the first two or three months the kids would trade off using stools," says Juliet. "But then the stools would be off in the corner. What's interesting is that the first graders never used the stools–but by the time you get to fourth grade you're so accustomed to sitting that you literally have to train to stand."

Students don't stand all day long; most lessons are 15 minutes long, and between recess, lunch, and other breaks, students typically spend only a total of three to four hours on their feet. If they're tired, they can always sit on the floor. The desks are also designed to make it easy to stand–carefully fitted for each child's exact height, and with a bar at the bottom to prop up a foot and lean.

"The whole thing is in dynamic motion, says Kelly. "Instead of just standing like you would in line at the grocery store–which feels like a lot of work–the desk ends up supporting an organic spine-hip position."

The footrest moves, so students can fidget throughout the day–something that's particularly helpful for kids with ADHD. "These are kids who would have been punching and pinching their neighbors, or otherwise kind of acting out in class," says Juliet. "Not only does the research show a dramatic increase in concentration, but that's what our own teachers at our school have reported as well. Kids are way more attentive at a standing desk."

For students, it's a way to get activity that they otherwise wouldn't. A large Kaiser Family Foundation study found that kids are spending 7.5 hours in front of screens each day. "Combine that with the six hours a day they're at school, and the fact that pretty much no kids walks to school anymore, they sit doing homework, they sit during meals," Juliet says. "We estimate that kids are spending 80% to 90% of their waking hours in sedentary positions."

Even if kids do an after-school sport, research shows that a small amount of exercise can't offset general inactivity. "Your sitting basically cancels out the positive effects of the workout," she says. "Even if these kids are spending an hour after school playing soccer or another sport, if they're literally spending every other waking hour in a seated position, it doesn't even matter that they're doing a sport, because it's still considered a sedentary lifestyle."

After the positive response to the first few classrooms in the school, the Starretts asked other teachers if they would also like to switch. Every single teacher in the school said yes. The ordinary classrooms, with traditional desks, are starting to look noticeably worse, Juliet says–while the standing desks are beginning to look normal.

"It makes the sitting classrooms honestly look ridiculous," she says. "If you go into the fifth grade classroom in our school, you have a bunch of kids who are 5'6″ hunched over at these little kiddie desks. Before, no one would have ever noticed because that's how it's always been done."

Now, the school is raising funds for the new furniture, and the Starretts have launched a new nonprofit called StandUpKids to help make it easy for other schools to make the switch. Through a partnership with DonorsChoose, they're helping facilitate donations.

"What was great about DonorsChoose was it gave the opportunity to go around the bureaucracy," Kelly says. "School districts have real fixed costs. Asking them to invest $150,000 per school is a big ask." The Starretts hope to raise a $1 million matching grant to support donations for individual schools across the country.

The new StandUpKids website outlines the science behind the benefits of standing desks for students, and makes the case for funders to support these programs.

"Right now a lot of donors think, okay, public schools don't even have pencils–so it would be frivolous to fund a standing desk when schools don't even have basic supplies," Juliet says. "We feel like our mission is to really change the mentality there. We're actually harming our children by putting them at sitting desks all day, and that the sedentary situation in this country is a legitimate public health crisis. This is not a frivolous expense."

In 10 years, the couple hopes to help push every public school in the U.S. to stand up. "We just think it's the most significant public health intervention since vaccination," says Kelly.