SAMSO, Denmark — On a balmy Monday afternoon earlier this month, Sebastian Lukas, 27, watched from across a clearing as his third- and fourth-grade students whittled branches into spearheads with sharp knives.

His gaze turned to another group, who were supposed to be working on math problems. Two students, perched on a log, scrambled to produce their textbooks, just in time to look busy.

Lukas began the year teaching in a classroom like any other, in Samso Frie Skole, a school on the Danish island of Samso. But when the novel coronavirus pandemic struck, the school, like many across the country, embraced a new way to hold certain classes: almost entirely outdoors.

Instead of sitting at desks, Lukas’s students wander through a rambling woodland, lush with trees and crisscrossed by dirt tracks.

As countries grapple with how and when to restore students to classrooms, a growing number of schools have embraced outdoor learning — especially in the highly regarded Nordic education systems, where the model had already begun to gain momentum.

When many Danish schools reopened in April, Prime Minister Mette Frederiksen urged teachers to allow for as much time outdoors as possible, as a precaution against the spread of the virus. In Norway, education and health officials also recommended that classes meet outside.

Out of nearly 200 Norwegian schools willing to respond to a recent survey by researchers Ulrich Dettweiler and Gabriele Lauterbach, the results of which have not yet been published, more than half said they had begun to provide more outdoor classes. Researchers in Denmark said they had observed a similar trend.

Some countries, including Germany, have a tradition of outdoor preschools and kindergartens, which have begun to catch on in the United States as well. The pandemic may drive more countries to experiment with the model for older students.

With educators and policymakers around the world watching with interest Denmark’s relatively smooth reopening, advocates for outdoor schooling say they hope newfound acceptance of the approach will outlive the pandemic.

‘It’s better to be here’

Samso, a sparsely populated, energy self-sufficient and carbon-neutral 44-square-mile island that was once a meeting point for Vikings, is a windy, hour-long trip by ferry from the mainland village of Hou.

The Samso Frie Skole — a private school funded, like many others in Denmark, in large part through public grants — first pondered the move outdoors long before the pandemic. Coronavirus accelerated those plans.

The new, forested area, surrounded by grain fields, includes old farmhouses, where students will be able to take shelter in bad weather, according to principal Anna Mattsson.

“It’s going to be a combination” of indoors and outdoors, she said. The aim is to have students learn outside several times a week, with fluctuations based on weather.

No one at the school said they were worried about the impending winter.

“We’re used to it,” said Rikke Ulk, the chair of the school’s support association. “It’s a matter of dressing well.”

Until the new buildings are ready, students must walk or bike more than a mile from their old classrooms to their new forest school. Teachers haul some of the younger children in carts affixed to bicycles.

Milling about before one such shuttle ride on a September morning, Noa, 11, said she liked the new school setup.

It’s “just so beautiful — it makes me happy,” she said.

After the 10-minute trip, students gathered in clusters beneath the trees, some wielding a book in one hand and a branch in the other. As the day progressed, teachers incorporated the surroundings into their classes. Children crouched to examine beetles and other insects during a biodiversity lesson.

During a physical education class, older students hoisted stones.

Much of the classwork continued as it would have indoors. During breaks, students played chess.

Some said they preferred certain aspects of learning inside.

“Sometimes, it’s better just being in the classroom, so we can focus,” said Sally, 12.

Cian, 9, an aspiring cook or robot engineer, disagreed. “It’s better to be here,” he said, holding his math book. “It’s cozier.”

Lukas said outdoor class works better for some students than others. “But some kids who have a hard time sitting love to come out here,” he said, and some students who struggled to focus on math indoors have shown aptitude outside.

The outdoor advantage

Researchers say outdoor teaching, implemented carefully, can have benefits.

“Educators have observed that children are calmer in the forest,” Natalija Gyorek, a forest school advocate in Slovenia, said in an email.

Students taught outside display higher motivation levels than their peers in classrooms, said Karen Barfod, a professor at VIA University College in Denmark who studies outdoor schooling. Those who study outside for at least two hours a week also tend to achieve somewhat better reading test scores, according to one study, she said.

One of the most commonly accepted Danish arguments in favor of outdoor schooling centers on health benefits, said Mads Bolling, a researcher at the Steno Diabetes Center Copenhagen. Students are able to avoid the adverse affects of sitting still all day.

But he cautioned potential disadvantages are not yet fully understood, and some research suggests outdoor schooling appears to provide the most for children who are already highly motivated.

For teachers, the switch to outdoor learning can be challenging, too, said researchers Dettweiler and Lauterbach. “You need to practice,” said Dettweiler.

A survey of hundreds of Norwegian schools conducted by Dettweiler and Lauterbach raised questions about whether outdoor schooling might actually make social distancing more difficult. Some teachers said it was difficult to “separate the children when they’re outside,” said Lauterbach.

The shadow of winter

For many teachers in Denmark, the benefits to outdoor learning appear to outweigh the downsides, Dettweiler said. Danish and Norwegian professionals active in the field said they have received a growing number of inquiries from colleagues around the world.

Even if outdoor class may not be practical for all schools or in all climates, said Bolling, it is not an all-or-nothing proposition. Samso Frie Skole plans to be flexible about which classes meet outside and which do not, and other schools can modulate accordingly.

The late summer months were a good time to begin the experiment, all seem to agree. When the school day comes to an end, there’s no bell. Instead, Lukas whistled, summoning his students and sending them back to the old school building.

Sally, 12, who expressed reservations about outdoor work, was among the slowest to pack up after her class had ended. She did not want to leave.

She said she was not afraid of spending more time than usual outdoors during the coming months of cold.

“It will be fun,” she said, “to experience nature in four seasons.”