Some of life’s greatest lessons are learned on a school playground – how to share, how to lose gracefully, how to just get along with others.

That’s why Maine’s elementary schoolchildren need a daily 30-minute recess, said Sen. Rebecca Millett, D-Cape Elizabeth, who is sponsoring a bill to make it a requirement.

“Today far too many of our children don’t get meaningful physical activity,” Millett said, presenting her bill at a public hearing Wednesday before the Legislature’s Education Committee. Representatives from health organizations and the state teachers’ union supported the bill.

Numerous studies have shown that exercise helps students focus, learn and be less disruptive in class by getting the blood flowing. Some classes have incorporated bouncy balls as seats to help fidgeting children, a nod to the idea that children need to move.

“Intuitively we know that if we stay fit, we feel refreshed, recharged and reinvigorated,” Millett said.

The state Department of Education, the Maine School Board Association and the Maine School Management Association opposed the bill, saying it was a mandate that would take away from local decision-making and would require schools to take the time to document that they were fulfilling the requirement.

Children who are elementary school-age should be getting an hour of exercise a day, according to the Centers of Disease Control and other health organizations. That hour should include muscle strengthening activities, such as gymnastics or push-ups, and bone strengthening activities, such as jumping rope or running, at least three days per week.

“Active kids are healthier kids. Active kids learn better,” said Victoria Rogers, a pediatrician and childhood obesity specialist at the Barbara Bush Children’s Hospital at Maine Medical Center and director of the “Let’s Go” exercise program.

“I know firsthand how hard it is to do this work, and that there are all these demands that get placed upon schools,” said Rogers, who is the director of the “Let’s Go” exercise and healthy eating program used in some schools. “We can help.”

Maine elementary schools have recess, but there is no mandatory minimum time. Students are also occasionally kept inside on very cold or very hot days for safety reasons, under state law.

Maine does require students to take physical education classes in kindergarten through eighth grade, but doesn’t specify for how long. Only five states and the District of Columbia require the recommended 150 minutes of physical education classes a week, according to a 2016 report by Shape America, the Society of Health and Physical Educators.

Most Maine elementary students only get phys-ed one or two times a week.

Millett’s bill would allow the 30 minutes of daily activity to include any combination of recess, recreational classroom activity or physical education.

“Classes in physical education are certainly an important part of exercise and team-building skills for school-age children. But unstructured play time is as important as the classroom skills,” said Lois Kilby-Chesley, the president of the Maine Education Association, the state teachers’ union. The MEA said a survey of its members found that some schools dropped recess during mandated testing days because of time constraints.

Millett’s bill would also bar schools from punishing a child by not allowing them to go to recess or get physical activity.

The committee will vote on the bill in an upcoming work session.