“[Riverside] is like my laboratory,” Huvos says. Her small, private program serves mostly “somewhat more affluent families.” In West Virginia, where the average monthly cost of center-based child care runs around $560, Riverside’s monthly $400 price tag is relatively steep, since that price only gets kids four days of care per week, and just three and a half hours each day. By and large, Riverside only works for parents who can afford to stop work and be available to pick kids up at 12:30 p.m. (or who have a full-time nanny or relative who can step in).

This bothers Huvos. “It’s become this unique, privileged thing: putting kids outside to play,” she says. Well-heeled parents realize, she says, that “this is what’s going to give your kid an academic advantage. This is what’s going to give your kid life success.” She hopes that if “affluent folks [are] demanding it,” more early education programs will emerge to provide more kids—of all backgrounds—more time outside.

As this happens, getting the details right will be important. How can—how should—early-education programs balance the competing demands of academic development and outdoor play? Most kids could benefit from more time outside, but it’s hard to imagine that they don’t also need time with interesting, vocabulary-rich books.

Figuring out that balance matters even more when schools are welcoming populations that are likely to struggle academically down the line. In the United States, achievement gaps between children from wealthy and low-income families appear well before kindergarten, and evidence suggests that children who start elementary school behind on critical skills tend to stay behind. If children arrive in pre-K with weak language development and academic skills, early educators may rightly feel pulled to focus on these. Sure, skilled educators can integrate math or reading instruction into time spent outdoors, but there are only so many hours in the day, and a recent study suggests that academically focused pre-K programs are particularly good at boosting children’s early math and reading abilities before—and into—kindergarten. It also found that “high-dose academic” preschools were uniquely effective at raising African American children’s math and reading skills.

Is it possible to capture the benefits of unstructured time in nature within the structures of public early education? Mundo Verde, a Pre-K–5th-grade charter school in Washington, D.C., is trying. Its model is defined by three components: student-driven learning, a focus on sustainability, and a Spanish-English dual-immersion program. The school gets kids outdoors by organizing learning into “expeditions”—students dive deeply into a topic, often culminating in an excursion that allows them to expand on what they’ve been doing in class. For example, when Mundo Verde second-graders study rocks, they visit the nearby Luray Caverns and collect fossils at Calvert Cliffs. At the end of a unit on balls, the school’s preschoolers design ball games to play with classmates in a nearby park.