Three boys are totally covered in mud - and their teachers say it's the best way for them to learn.
Two girls are painting leaves.
Other kids are playing with ropes, climbing trees or whittling a stick with a potato peeler.
This is "play-based learning", and many New Zealand schools are embracing it now that the new Government has freed them from the former national standards.
Linda Cheer of Napier's Longworth Forest School, who runs a consultancy on play-based learning, says interest is "growing very fast throughout New Zealand".
"We are fully booked going into next year to support schools," she said.
But she sees a divide between play-based schools and more traditional schools which still expect teachers to teach from the front of the classroom.
"There are many teachers who come to our workshops who have quite sad stories to tell," she said.
"They say, 'I know this is the best for children, but I'm the only one in the school who believes in it and I'm battling the whole time'."
The play-based approach is based on evidence that everyone learns best when they are engaged emotionally as well as intellectually.
Neuroscience educator Nathan Wallis said children needed to develop an emotional "disposition towards learning", by finding that it was fun, before learning "repetitive patterns" such as words and numbers.
"A play-based environment very clearly shows that the kids develop a positive disposition. They develop perseverance, creative problem-solving," he said.
In the mud on a wet day in a Conscious Kids holiday programme at Auckland's Meola Reef Reserve, the children invented a fantasy about "golden mud".
"It brings out their creativity," said Conscious Kids director Ann Langis.
When their boots got stuck in the mud, she said, they learned about suction.
"If they don't have that first-hand experience, it's very difficult to get that child to be interested in a concept like that," she said.
They also develop their oral language by talking to each other - an important factor for Auckland's many children who speak English as a second language.
"Those kids are not going to speak in a big circle, but when they are playing they start jabbering away," she said. "How else are they going to learn the language?"
Claire Edwards, who uses play-based learning with new entrants at Bayswater School on Auckland's North Shore, said today's children were starting school with weaker oral language and fine motor skills than in earlier decades.
"We have at least three teachers in our room," she said. "Two will be taking small groups for reading and writing and maths, and the other one will be with the children, engaging in their play and trying to elicit more oral language from them and deepening their ideas."
Play-based teachers offer children "provocations" to spark creative play. At Meola Reef they put out paints and ropes. At Bayswater they have tried big cardboard boxes, wool, fabric, plastic bottles, bottle caps and lolly sticks.
"From observing what the children do within their play, and what they use the provocations for, we find their collective interest, and we then scaffold the curriculum around the collective interest," Edwards said.
"Teachers generally tried to do things that they thought would be interesting for children.
"This way, we know it's interesting, because we have seen them do it."
Auckland Primary Principals' Association president Helen Varney, whose Target Rd School in Glenfield has been trialling play-based learning for junior classes since 2016, said she did not think schools were philosophically divided about it.
"Aspects of play-based learning have been in NZ Year 1-2 classrooms for years," she said.
"What is happening is teachers are more aware of the opportunities for learners to develop their knowledge and skills through play."