Bringing adventure into play
The ideas began in post-war cities, when children used empty and derelict spaces to play in. It then spawned a whole adventure play movement.
But how do children play now and what value do they get from it? Are there now fewer opportunities, especially for urban kids, to play outside?
Later this month in Glasgow a "Play Summit" is being held which brings together experts from both this country and further afield to discuss these and other issues.
In Glasgow's East End, just a short distance from the site of the Commonwealth Games, the Baltic Street Adventure Playground is taking shape.
There are mounds covered in wood chip, an old tree branch, a pile of bricks, a couple of old containers and a tree house.
When it opens fully before the summer, the playground will, in essence, remake itself each time a child comes to play.
Proof of that can be seen in how children have been using old plastic ventilation tubes for different games.
"I've seen those tunnels used in about 40 different ways - rolling over, rolling under, rolling through, assault courses," says lead play worker Robert Kennedy.
He adds that the fallen tree branch has been used as a platform, a springboard or incorporated into a game of tig.
"You need to try and be an observer as much as possible," he continues, "because I don't want to be directing their play but I've got to make sure they're protected and safe while they're here.
"Trying to find that balance is very hard but it's very beneficial when they know that I'm not just going to step in every time they need to lift a bit of wood somewhere."
A play worker is on site whenever the playground is open. It is being made as a public art commission and the group behind it is Assemble, a London-based art and architecture practice. They came into an area which is undergoing huge changes.
"One of the things that really struck us," says Assemble designer Amica Dall, "was that the timescale that regeneration efforts like that work on are quite meaningless in the context of a child's lifetime and so we wanted to do something that was immediate."
Children have always played, of course, but some argue that modern childhood can actually mean that their horizons are shrinking.
"In countries like Germany and the Netherlands and the Nordic states there's a basic recognition of, if you like, children's right to freedom," says Tim Gill, who is a researcher and writer on children's play and free time.
He argues we need to be thinking about "a child-friendly community and you can see that if you go to towns in Denmark or Sweden, you just see more children out and about and you see a sense that people just think that's fine and everyday and part of growing up."
This month's "Play Summit" will discuss, among other things, adventure play. It had its roots after World War Two, when children began playing on empty sites in cities.
"Urban areas which were no longer a place in themselves, they were in-between places," says Kate Gray, a director at Collective, an Edinburgh-based arts organisation which has organised the summit.
"They used those places to play in and the adventure playground movement coming out of that which was really around having play workers on site to work with children and have no fixed play architecture.
"It was much more about children creating and taking down again and recreating from scratch. And I suppose in the time of digital culture it might be interesting to think about the difference between creating virtually and creating in the real world."
At the Baltic Street Adventure Playground, play worker, Robert Kennedy pulls back a blue, tarpaulin weighed down by puddles to reveal what will eventually become a climbing wall. This was part of a promise to one of the children who visited the playground.
"When I was a child, there was nothing I liked better than running or playing on dykes, playing hide and seek, building dens," says Mr Kennedy, explaining why he feels so passionately about what he does.
"I see children not getting out today possibly as much as they should. A young girl helped build our tree house and she was telling other young people that she built it and it was hers and that's the whole point of this playground, it's for them to adopt it as their own.
"In five years' time, 10 years' time - whatever it may be - I'll not be here.
"One of them will come and take my job off me and that's what I'm looking forward to because it means I've taught them well."