Getting kids to sit still in class has been a challenge for years. So some schools are now asking them to stand.
And the kids like it!
"When I get into school, I like to stand up but after recess I like to sit down, rest my legs," one student told NBC News' Joe Fryer.
New standing desks being tested out in schools around the country are showing benefits in class and with test scores. At Alexandria Country Day School in Virginia, for example, they're the new normal for 5th through 8th graders.
"The research is very clear that standing is far healthier than sitting, and we wanted to do something bold," said school head Scott Baytosh.
Researcher James Levine (who created the first treadmill desk) says it's important to have students move around during a school day, and it improves not just bodies but brains: Test scores are showing 10 to 15 percent jumps in schools with standing desks as an option.
"The data consistently demonstrate that when children are allowed to move during their school day, they learn better," said Levine.
But it's important to mix it up. When students get tired of standing, they're encouraged to take a seat or, as in Vallecito Elementary in Northern California, swing their legs on a part of the desk called the "fidget bar."
Turning an elementary school into a mixed stand/sit environment costs about $150,000, said Vallecito parent Juliet Starrett, who helped raise money for the desks.
"If these desks are going to last 15 or 20 years, this is a single-fixed cost but a long-term investment in kids' health," she said.