What the Trees Outside Your Child's School Are Doing to Their Brain
A decade of research now shows that green space around schools changes how children's brains develop - not metaphorically, but structurally. The children with the least access to it are the ones the evidence says need it most.
Something odd happens to children's brains when they spend time around trees. Not in the way you might expect - not the fresh air, not the exercise, not the break from screens. The trees themselves, or more precisely the greenness around them, appears to change how their brains develop. And the children who get the least of it are often the ones who need it most.
A study tracking over 2,500 primary school children in Barcelona found that those with more green space around their school showed a 5% greater improvement in working memory over twelve months, and a 6% improvement in what researchers call superior working memory - the ability to hold and manipulate information at the same time. Their inattentiveness dropped too. These weren't children doing forest school or outdoor education programmes. They were just going to schools that happened to have more greenery nearby.
That was back in 2015. The research has only got more striking since.
This wasn't just about wealthier families living in leafier areas. The associations held even after accounting for household income and neighbourhood deprivation. Green space appeared to be doing something to children's brains over and above the advantages that come with money.
And those brain differences weren't abstract. They were linked to better academic performance and fewer attention problems. The green space didn't just correlate with better outcomes - the brain changes helped explain why.
As the greening progressed, children in the intervention schools showed improved selective attention compared to children at control schools. Their mental effort during cognitive tasks increased too, measured through pupil dilation during tests. And their prosocial behaviour - the kind of cooperative, considerate actions that teachers notice - improved over time.
These weren't dramatic, headline-grabbing changes. They were steady, measurable shifts in how children thought and behaved. The kind of thing that compounds over a school year.
A separate systematic review of green space interventions in schools, also from 2025, found similar patterns: two studies reported significant increases in attention after children played or had breaks in green spaces. Greening playgrounds had mainly positive effects on social and mental health.
The decline is sharpest for unsupervised outdoor time. Between 2013 and 2019, the proportion of children spending time outside dropped from 81% to 74%. The 2025 Children's People and Nature Survey for England found that only 31% of children said they could easily walk to woods or forest, and just 21% to fields or countryside. If you don't live near it, you don't get it.
There's something worth sitting with in that last number. The brain benefits of green space aren't evenly distributed. Children in urban areas, children from lower-income families, children in flats without gardens - they have the least access to the thing the research says matters. A 2025 study in Belgium found that the amount of green space at a child's school was directly linked to their attention scores, and that link didn't depend on whether the child had a garden at home. The school grounds were doing the work.
This doesn't diminish the case for green space. If anything, it strengthens it. Trees are doing double duty: providing the sensory environment that appears to support attention and emotional regulation, while simultaneously cleaning the air that children breathe during the hours their brains are working hardest.
But the direction of the evidence is clear, and it has been for a while. Green space around schools matters for how children think, focus, and behave. Not in a vague, nice-to-have way, but in a way that shows up in brain scans and test scores. Schools that invest in greening their grounds aren't just making them look nicer. They're changing the environment in which children's brains develop.
The next time you walk past your child's school, look at what's growing there. It might matter more than you think.
A study tracking over 2,500 primary school children in Barcelona found that those with more green space around their school showed a 5% greater improvement in working memory over twelve months, and a 6% improvement in what researchers call superior working memory - the ability to hold and manipulate information at the same time. Their inattentiveness dropped too. These weren't children doing forest school or outdoor education programmes. They were just going to schools that happened to have more greenery nearby.
That was back in 2015. The research has only got more striking since.
Your child's brain is literally shaped by greenness
In 2025, a team from King's College London and the University of Melbourne published findings from one of the largest studies of its kind. They followed 7,102 adolescents over two years, scanning their brains and tracking their school performance. The results, published in Biological Psychiatry, showed that children who grew up with more green space around them had measurably different brain structures - greater cortical surface area and volume in regions linked to attention, memory, and emotional regulation.This wasn't just about wealthier families living in leafier areas. The associations held even after accounting for household income and neighbourhood deprivation. Green space appeared to be doing something to children's brains over and above the advantages that come with money.
And those brain differences weren't abstract. They were linked to better academic performance and fewer attention problems. The green space didn't just correlate with better outcomes - the brain changes helped explain why.
What happens when you add green to a school
If growing up near trees changes brains, what happens when you deliberately make a school greener? A 2025 intervention study set out to test exactly that. Researchers worked with primary schools to redesign their playgrounds - adding native plants, creating varied vegetation, building height variation into the landscape.As the greening progressed, children in the intervention schools showed improved selective attention compared to children at control schools. Their mental effort during cognitive tasks increased too, measured through pupil dilation during tests. And their prosocial behaviour - the kind of cooperative, considerate actions that teachers notice - improved over time.
These weren't dramatic, headline-grabbing changes. They were steady, measurable shifts in how children thought and behaved. The kind of thing that compounds over a school year.
A separate systematic review of green space interventions in schools, also from 2025, found similar patterns: two studies reported significant increases in attention after children played or had breaks in green spaces. Greening playgrounds had mainly positive effects on social and mental health.
We know this, and children are still losing it
Here's the uncomfortable part. While the evidence piles up, children in England are spending less time outdoors than they used to. Research shows today's children play outside for roughly half the time their parents did - about an hour and twenty minutes after school, compared to over two hours for the previous generation.The decline is sharpest for unsupervised outdoor time. Between 2013 and 2019, the proportion of children spending time outside dropped from 81% to 74%. The 2025 Children's People and Nature Survey for England found that only 31% of children said they could easily walk to woods or forest, and just 21% to fields or countryside. If you don't live near it, you don't get it.
There's something worth sitting with in that last number. The brain benefits of green space aren't evenly distributed. Children in urban areas, children from lower-income families, children in flats without gardens - they have the least access to the thing the research says matters. A 2025 study in Belgium found that the amount of green space at a child's school was directly linked to their attention scores, and that link didn't depend on whether the child had a garden at home. The school grounds were doing the work.
It might be about the air as much as the view
One of the more surprising findings from the Barcelona research was that air quality explained a large chunk of the green space effect. When researchers added traffic-related air pollution to their models, it accounted for 20 to 65% of the link between school greenness and cognitive development. Trees filter particulates. Cleaner air reaches developing brains. The cognitive benefits of green space aren't purely psychological - they're partly biological.This doesn't diminish the case for green space. If anything, it strengthens it. Trees are doing double duty: providing the sensory environment that appears to support attention and emotional regulation, while simultaneously cleaning the air that children breathe during the hours their brains are working hardest.
What this means at the school gate
None of this is a prescription. You can't dose your child with exactly the right amount of tree exposure and expect a specific result. Brains are complicated. So are children.But the direction of the evidence is clear, and it has been for a while. Green space around schools matters for how children think, focus, and behave. Not in a vague, nice-to-have way, but in a way that shows up in brain scans and test scores. Schools that invest in greening their grounds aren't just making them look nicer. They're changing the environment in which children's brains develop.
The next time you walk past your child's school, look at what's growing there. It might matter more than you think.
Sources & Further Reading