Forest “friendly bacteria” schools boost children’s immune systems

First developed in Denmark in the early 1950s, forest schools have been steadily gaining momentum across the globe over the past two decades. The practice, which sees children spending their days learning outdoors among the trees, offers young ones a host of physical and emotional benefits.  Kids who are educated outside come in contact with a variety of "friendly bacteria," which can boost their immune systems by increasing the microbial diversity on their skin and in their guts. And forest schools, which can now be found on at least four continents, have also been shown to improve mental health and instill a sense of responsibility for the natural world.

Forest boost children's immune systems
https://www.science.org/doi/10.1126/sciadv.aba2578

Denmark forest schools:
https://www.theforestschoolfoundation.org/background-information-history