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At about 10 am local time on school playgrounds across the United States, kids are climbing on jungle gyms and whooshing down slides. They’re playing bandage tag or foursquare. They’re walking around the track, quietly catching up with their friends.

Those are the lucky ones. Recess, experts agree, is one of the most crucial parts of a child’s school day.

“When kids get to play, and especially outside, they get to feel joy, they get to feel connection, they get to feel like they belong at school,” Elizabeth Cushing, CEO of the nonprofit Playworks, told me. “That’s the kind of experience we all want for them.”

But parents and advocates around the country say that, too often, kids are now spending recess in their classrooms, where they don’t get the full benefits that outdoor play can provide.

In Western states, extreme heat is increasingly keeping kids indoors, said Allison Poulos, a professor at Arizona State University’s College of Health Solutions. In one study conducted from July to September — the hottest months of the year in Arizona — her team found that kids were inside for recess about 40 percent of the time.

In colder areas, a variety of factors are at play. “We’ve heard a principal say he didn’t want the kids messing up the playground,” said Shanée Garner, executive director of Lift Every Voice Philly, a parent organizing group. “We’ve heard some folks say there’s no staffing. We’ve heard other folks say that the kids don’t get along with each other.”

When kids have recess inside instead of on the playground, they’re typically sedentary and often watching a movie, experts told me. In the Arizona study, kids who had recess in their classrooms were less ready to learn when lessons resumed than kids who actually got to play outside.

Now, families around the country are pushing for more outdoor time, and researchers are exploring ways that schools can get kids outside — or at least get them more active indoors — as the climate changes. These changes are necessary, advocates say, because without play, kids can’t learn.

“Recess is a very important period and time for children’s growth........

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