The Globe and Mail

At the Coombes school in southern England, the playground looks like an arboretum. Narrow paths snake through the shrubbery past apple, willow and walnut trees. There is a pond, two labyrinths, a garden and plenty of good spots to dig for worms. Lessons often take place outside.

It is the creation of Sue Humphries, an educator who, over four decades, transformed the once barren yard into a verdant outdoor classroom because of her conviction that sitting in chairs is not the best way for children to learn. There is mounting scientific evidence that she is on to something and it has become part of a growing outdoor movement that could transform the way school yards are designed and built.

Studies suggest that interacting with nature can help children pay attention, motivate them to learn and improve both classroom behaviour and scores on standardized tests. Neuroscientists and psychologists are investigating why nature is good for young brains and how being around trees and shrubs helps recharge the circuitry that children use to focus on a page of fractions or a spelling test.

The dominant idea about how nature helps kids learn is called “attention restoration theory” and is based on evidence that humans have two different kinds of attention. One is directed and takes effort and concentration. It is what students use when they do long division, what adults use to get a memo written at work.

“You only have a certain amount of it,” said University of Michigan brain scientist Marc Berman.

Directing our attention to a task is very different from having it captured by something in the environment, a butterfly flitting by the window or a car speeding down the street. This is involuntary attention.

“You don’t really have a choice. It just happens. It is activated when something interesting or surprising or loud happens and automatically grabs your attention,” Dr. Berman said.

Engaging the involuntary system allows the directed-attention system to rest and recover, and getting outside in a natural setting is a very good way to switch from one system to the other. Nature offers “soft fascination,” he said. It is interesting enough to engage us, but not riveting enough to absorb us. Urban settings aren’t as restful because they require more vigilance to avoid cars, buses or other hazards. Television, movies and computer games may be too absorbing to allow the circuitry involved in paying attention to recharge.

In one recent experiment, Dr. Berman found that undergraduates did better on attention and memory tests after a stroll through an arboretum than a walk through downtown Ann Arbor, Mich. He is now using brain imaging to learn more.

Even looking out the window at trees or parkland can be “cognitively restorative,” according to some studies, said Nancy Wells, a researcher at Cornell University in Ithaca, NY.

She and others are working to determine what “dose” of nature is required to make a difference.

“How much is enough to have a useful effect?” asks Andrea Faber Taylor at the University of Illinois. “I suspect it has to be daily.”

Since children already spend time in school yards, it seems to make sense to start there. But can trees and grass in an urban setting really make a difference?

That’s the question Frances Kuo, also at the University of Illinois, is hoping to answer with a large study that involves 470 schools and half a million students.

The school yards are assessed through a variety of measures, including aerial photographs. She and her colleagues are now evaluating whether children at the schools that have more greenery tend to score higher on standardized tests.

This kind of research is challenging because scientists have to take into account many factors that can affect how well children do in school, like whether they come from poor families.