Thirty-five miles south of the Capitol, just west of Interstate 95 and its infernal traffic, is a quiet, oft-overlooked swath of green — a national park founded during the Great Depression to give city kids an escape into nature.

For decades, it served that purpose. But sometime in the 1980s, the children stopped coming, and since then — save for the occasional church group or scout troop — the park’s rough-hewn cabins and dining halls have sat mostly empty.

Now that could change.

NatureBridge, a California-based nonprofit organization that runs three- to five-day environmental education programs in some of the West’s most iconic parks, wants to turn this place — Prince William Forest Park, one of the largest green spaces in the Washington area — into an outdoor classroom for local students.

The organization is running a pilot program this month with two groups of middle-school students from Prince William County. If it goes well, the park could return full time to its roots as a place for kids to learn about — and enjoy — the natural world.

“This is a test of local demand and support, and we’re hopeful that the community will really rally around it,” said Vanessa Morel, NatureBridge’s D.C. director.

Some school systems — such as those in Arlington, Montgomery and Prince George’s counties — have been sending students into the woods for overnight environmental education experiences for years. But those are generally for just one night. And many area schools limit outdoor education to field trips of a few hours or a day.

If NatureBridge decides it’s feasible to establish a full-time program at Prince William Forest, it will be one of the few — if not the only — longer-term residential programs in Northern Virginia, and will try to draw classes from across the Washington metro area.

Students would be charged a fee to attend, and scholarships would be available for those from low-income families.

Last week, the inaugural group of students — seventh-graders from Triangle’s Graham Park Middle School — arrived for a three-night stay. Led by NatureBridge instructors, they spent each day doing the kind of hands-on science that means tramping through the woods, exclaiming over creekside discoveries and ending each day ready for sleep.

“I like it here,” Claire Willard, 13, said as she clambered over fallen trees, picking her way down a steep slope toward a water-quality sampling site on Quantico Creek, a tributary of the Potomac River. “The clock runs a lot faster when I’m doing stuff than when I’m sitting down doing math homework.”

Prince William Forest sprawls over 15,000 acres adjoining Marine Corps Base Quantico, whose artillery fire is audible from the park’s creek beds and low ridges. Earlier this month, the park’s delicate forest-floor wildflowers were in bloom, and its canopy of oak and poplar trees were still a bright, new-leaf green.

The students identified plants and hunted for mayflies, stoneflies and water striders. They discovered snakes and scat. They played a game of rock-paper-scissors to learn how a meadow grows into a mature forest and a version of tag to understand how predators affect the deer population.

Those activities bring concepts to life in a way textbooks simply can’t, said Graham Park science teacher Laura Schubert.

“I can talk about stuff, we can see pictures, but there’s nothing like having all this,” Schubert said as she gestured at the forest.

Not everything was academic. Kids also skipped rocks, caught frogs and dunked their heads in the creek. Those are valuable experiences in an era of ubiquitous computer and cellphone screens and intense focus on preparing for standardized tests, say advocates for environmental education.

“Getting kids reconnected to the outdoors has all kinds of benefits for their health and their education and their inspiration,” said National Park Service Director Jonathan B. Jarvis, who helped direct NatureBridge to Prince William Forest, where he began his career as a ranger in the 1970s.

“The first time they see stars or see wildlife or hear quiet — that can really make an impression,” Jarvis said.

The federal government had the same conviction three-quarters of a century ago, when Prince William Forest was established through the purchase of more than 100 failing family farms and a shuttered pyrite mine.

Then called the Chopawamsic Recreational Demonstration Area, it was a model for a new kind of park — not a far-off postcard landscape, like Yosemite or Yellowstone, but a more humble oasis easily accessible to the urban poor.

The federal government proclaimed in a 1936 film that these new green spaces — 46 in two dozen states — would help raise “a crop of sturdy citizens of a thoughtful republic with a clean, sound mental attitude.”

Thousands of members of the Civilian Conservation Corps descended on Chopawamsic to build five camps, complete with sleeping cabins, arts-and-crafts buildings, infirmaries and mess halls.

Those camps — racially segregated until the 1950s — were run by social service organizations as summertime refuges for children from Washington and other nearby places.

“It’s the first time most of the children have ever vacationed outside the District,” one camp director told The Washington Post in 1937. “They have never before known flowers they could pick, and daisy picking was the favorite camp activity our first night here.”

Now, as the Washington area emerges from the Great Recession instead of the Great Depression, it’s still true that many kids here don’t know what it’s like to unplug from urban life for an extended period.

Many Graham Park students said they had never been camping before and had certainly never hiked so many miles in the forest.

Principal Gary Anderson said that those students had been reluctant to make the trip to Prince William Forest, agreeing to come only after plenty of cajoling and reassurance.

“But talk to them now, and they’re so turned on to nature,” Anderson said. “What better experience could you have?”