In a patch of bush beside Melbourne's Merri Creek, five-year-old Rachael is perched in a tree. She's inched up and down several times, getting higher and prouder each time.

"I like climbing the trees," she grins, her sun hat lopsided. "I'm still learning."

Step into this clearing in the inner-north suburb of Northcote and the city disappears. A breeze ruffles the reeds and beetles are busy on mottled trunks. A sharp smell of mud wafts up from the creek.

Around Rachael, watched over by four educators and a parent helper, 27 other four and five-year-olds from Batman Park Kindergarten are deep in play.

They're here for their weekly session of bush kinder and while there's a camp toilet, a tarp as a picnic rug and high visibility vests for everyone, there's not a toy or swing set in sight.

Children are building a giant aquarium, collecting rocks as sharks' teeth and branches for coral. A raucous orchestra is playing stick instruments.

Two girls are rabbits in a nest they've made of grass clippings, while another group is crafting fishing rods from sticks and reeds.

The bush kinder movement in Australia is building momentum. ( Supplied: Lisa Clausen )

Screens and schedules give way to rocks and trees

Inspired by Scandinavia's forest preschools, the bush kinder movement in Australia is building momentum as growing numbers of educators and parents become convinced of the importance of nature play.

In the mud and in the trees, they say, profound learning is taking place.

At Batman Park, the program has become increasingly popular with families since it began seven years ago.

Children are dropped here one morning every week, with snacks, gumboots and at least one change of clothes.

After sitting in a circle for a welcome and a song or two, they spend the next three hours in the dirt, up trees, stomping in mud and climbing over rocks.

For children growing up in a regulated world of screens and schedules, educator Pieta Hulbert says the freedom and creativity of bush kinder offers children a myriad of physical, social and sensory benefits, and fosters independence, healthy risk-taking and problem-solving skills.

Pieta Hulbert an educator from Batman Park Kindergarten ( Supplied: Lisa Clausen )

As they play, they're immersed in the natural world, learning about the Indigenous history of the area — about its creatures and seasonal cycles — from Wurundjeri elders.

"It's so important for them, and there's a huge amount of joy in it for them," says Hulbert, who's led the program at Batman Park since its inception.

"People think that children need to be entertained all the time, but they really don't — and it's much better for them not to be."

The program runs year-round in all but the most extreme weather, and Pieta says the children relish even the coldest days.

"We jump on icy puddles and run through the frost on the grass — the kids absolutely love it," she says.

In any weather climbing trees is a favourite activity. Once a childhood staple, this endangered art has many lessons to impart.

"On a climbing frame you climb it and it's done. But there are so many variables in climbing a tree, even if you've climbed it before," says Pieta.

"A branch may have broken off, it might be slippery or wind might make it move differently.

"At bush kinder we try not to say 'be careful'. We say things like, 'Do you feel safe?' or 'Are you holding on in two places?', 'What's your plan to get down?'

"We want them to work out for themselves how to climb that tree in a safe and thoughtful way."

Nature teaches lessons in imagination and creativity

Bush kinder was pioneered in Australia in 2011 by Doug Fargher, director of Westgarth Kindergarten, also in Northcote in Melbourne's inner-north, who is passionate about its impact on children's wellbeing and development.

When children arrive at Westgarth's bush site in nearby parkland for the first time, they're often taken aback by the lack of equipment or structured activities.

But it's not long before their natural creativity erupts. "Children are really creative and really capable. They just need the opportunity to use their imaginations," Fargher says.

The children care for the space, picking up rubbish, planting trees and spending time with Wurundjeri elders and local rangers. They collaborate on projects like moving logs around, discover their own abilities and respond to being trusted, says Fargher.

At The Nature School in Port Macquarie there is no set schedule. ( ABC: Imogen Brennan )

"The children see themselves as strong and capable and they see each other that way too."

They're universal skills which aren't just for city kids.

Even fire has a lesson to impart

Before bushfire hit the community of Buchan, 350 kilometres east of Melbourne, in late December, Buchan Early Childhood Development Centre educator and coordinator Rocio Levings had been taking children into bushland near the small township since 2014.

"Just because children live in the bush doesn't mean they're spending quality time in nature as part of their daily life," says Levings, speaking to the ABC before the fires.

"Yes, we're surrounded by it out here, but that's different to children being let free in a safe, wild environment where they can explore and find their own connections."

Carrying string, compasses and magnifying glasses, every session normally includes a bushwalk led by one of the four-year-olds.

While educators watch from the rear, the leader has to decide whether or not the group will jump from a much-loved tree stump, when it's safe to cross several dirt roads, and if the children will take a shortcut.

At the "big hill" everyone votes on whether to run up it or not.

"There is so much learning just in that walk," says Levings.

Building resilience in young children is central to the bush kinder philosophy.

'We don't mollycoddle the kids'

"If the children pull themselves up by holding onto the sword grass their fingers will bleed, for example — but it's not the end of the world," says Levings.

"We don't mollycoddle them, we let them have the experience and then they teach other children not to hang onto the sword grass."

She says the children develop a profound bond with the landscape.

"They see what drought does, what the ground looks like when there's been no rain, what happens when people throw fishing lines or rubbish in the creek — the consequences of the interactions between human and nature," she says.

"They understand we are all part of that system and the more they see that connection with nature, the more likely as adults they will be to look after it."

Many children are also now seeing what fire can do to a beloved landscape.

Dr Sue Elliott, senior lecturer in early childhood education at the University of New England and an expert in natural play spaces, says this summer's horrific bushfires make the role of bush kinder even more crucial.

With many children deeply anxious about climate change, about smoke hanging over their backyards, or bushfires threatening their communities, Elliott emphasises the opportunities within bush kinder programs to teach children about the causes and impact of fire, while giving them tangible ways to help — whether it's revegetating an area or making pouches for orphaned joeys.

"There's a lot of anxiety among young children and we need to make sure we don't exacerbate that anxiety but instead create pathways for them to feel empowered and have agency," she says.

"The fires adds another layer of urgency to what we need to be doing with them."

Every bush kinder program undergoes rigorous risk assessments covering a range of scenarios, from fire to snakes and thunderstorms, and sites are selected carefully for access, visibility and natural boundaries.

"We have to be able to say to families, 'this is why we are doing this and this is how we're going to keep your child safe'," says Batman Park's Pieta Hulbert.

Buchan was badly affected by fire, but the bush will offer important lessons about revegetation and resilience. ( Facebook: Buchan Caves Hotel )

She's never had a serious injury at bush kinder, and sees more bumps and bruises in indoor classrooms.

Westgarth's Doug Fargher agrees: "We've noticed that children are more likely to hurt themselves on equipment that meets Australian standards with soft-fall underneath than they are in a tree."

Buchan's Rocio Levings thinks this is partly because in a wild setting, children instinctively take more responsibility for themselves and others.

"If we're walking over the rocks and one of our smaller friends is with us, the children all want to help them and make sure they're safe. That compassion comes out naturally at bush kinder."

Measurable improvement on behaviour

Pieta Hulbert says the bush brings a different mood.

"The kids are often more settled at bush kinder, more chilled out. We're dealing with less behavioural challenges," she says.

At Westgarth, Doug Fargher says, the slower pace deepens relationships and conversations between educators and children.

Such benefits have convinced many hesitant parents.

"In the beginning some parents said, 'We live in the bush, why do we need this? How will our kids get school-ready if they just sit in the bush and play?'," says Levings.

Now many of those same parents want to see the program extended into local schools.

"We need to break down that assumption that serious learning can only happen in a classroom," she says.

At Batman Park, Anita Barker — who admits her family doesn't do much camping — wasn't sure how her son Thomas would feel about bush kinder.

"But he's really embraced it and it's been a wonderful experience for him," she says,

"I remember rocking up here the first time and thinking, how is this going to go in the middle of winter? But he's never said it's too cold to go. They cope.

"If he comes home with a few scratches or he's dirty, he's fine with that.

"I realised that it was me who needed to change my thinking."

A 2018 report by the Kids In Nature Network, with partners including Westgarth, Parks Victoria and the Victorian Government, highlighted huge potential to engage more children in regular nature play.

The report found 330 groups across the state who run nature play, outdoor learning or bush kinder programs, and more than 110 others which wanted to establish programs but either didn't know how or lacked the resources and staff.

Sue Elliott says while Europe's forest preschools led the way, Australia's bush kinder movement will continue to grow with its own unique flavour.

"We are building on what has been done overseas but also translating it into what is relevant for our particular landscape, the Indigenous perspective, our geography, our flora and fauna and our socio-cultural context," says Elliott.

"Bush kinder has added a whole new layer of learning opportunities."

Bush schools are popular around Australia, including The Nature School in Port Macquarie which encourages bush play and bushcraft. ( Facebook: The Nature School )

While there's a huge appetite among educators for bush kinder programs, Elliott cautions against seeing nature as just another playground.

For bush kinder to be truly meaningful for children, she says, it must focus on leading them towards a deeper, more sustainable relationship with the natural world.

"It's about the relationship between humans and between humans and the Earth," she says.

Down by the Merri Creek, Pieta Hulbert, her clothes smeared with small muddy handprints, is watching those relationships blossom.

"Some people have said to me bush kinder is a fad," she says, as a group of children huddle intently around a tree trunk to examine an unusual bug. "But nature isn't a fad."