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.
But over the past decade, 100 schools have added trees, shrubs and gardens to their grounds. Dr. Kuo has been able to track whether the greenery is linked to an improvement in test scores in schools at which the demographics have remained the same.
"The initial findings look promising," she said.
Yale University's Stephen Kellert said it is smart to focus on practical fixes, like making school yards and back yards more enticing for children. But indoor spaces should also be rethought, he said, since people spend 90 per cent of their lives inside. Natural light, ventilation and other design elements may also help youngsters perform better.
At the Coombes school, the students range in age from 3 to 11 and spend about half of their time outside over the course of the school year.
Cam Collyer said that when he visited two years ago, his North American sensibilities were shocked by all the small nooks and crannies where children could find private spaces. He was also impressed by the poetic way Ms. Humphries was able to describe why it is so important to create a sense of the wild for every child. Mr. Collyer directs the school-ground greening program at Evergreen, a national charity in Canada. He invited Ms. Humphries to speak at All Hands in the Dirt, a forum on the topic being held this weekend in Toronto.
"She is an unlikely celebrity," he said. "But Coombes is arguably one of the best designed school grounds in the world."
Mr. Collyer credits the growing awareness of the need to get children out of doors to Last Child in the Woods a book by U.S. author Richard Louv, who coined the phrase "nature deficit disorder" to describe the disconnect between today's indoor children and the natural world. Published in 2005, it tapped into the unease many parents feel about the lack of unstructured time children have to explore the outdoors, especially compared to their own childhoods. Mr. Louv is the co-founder and chairman of Children & Nature Network, which works to connect children with nature.
That's Ms. Humphries's mission as well, one she argues is more important than how children score on standardized tests. The Coombes school does about average, but that, she said, is not the point. She knows how well her students respond to learning out of doors, especially boys, who many people feel are being short-changed in modern classrooms.
Now retired from teaching, Ms. Humphries has travelled to Japan, Sweden, Norway and the Netherlands to offer practical advice on how to rip up asphalt and create inviting landscapes even in small school yards.
"It is important to raise children with other species, with fruits, flowers and gardens so they can plant and grow and understand something about the cycle of nature. ...We owe the world this as well as the children."