The foundation scheme encourages learning through play
The first generation of children to follow "ground-breaking" play-based learning in Wales is starting school.
The foundation phase includes classes outdoors and experience of the environment. It starts with three and four year olds and extends up to the age of seven.
Education Minister Jane Hutt said it was a "radical new way of learning".
But a teaching union said staff were under "enormous pressure" to deliver, without the promised level of funding.
The foundation phase emphasises the importance of learning through play for children aged three to seven and requires a teacher pupil ratio of one to eight.
We believe that the pay-off of this radical new way of learning will be long-term and its impact will be felt for many years to come
Jane Hutt AM, Education Minister
Ms Hutt, who was officially started the scheme on a visit to Brynnau Primary School near Llanharan in Rhondda Cynon Taf on Tuesday morning, said: "The foundation phase takes a different approach to learning and a key feature is using the outdoors to encourage children to learn about conservation and the environment.
"In Wales we are lucky to have a fantastic outdoors and children will discover their environment, the seasons and the weather by exploring fields, woodlands and the outdoors looking for bugs and wildlife," she added.
Ms Hutt said they had drawn on experiences in Denmark, New Zealand and Italy and believed the "radical new way of learning" would have a long-term impact.
The school's head teacher Vanessa McCarthy said she welcomed the changes.
"I think that the principles of the foundation phase are to be applauded and the potential benefits will be significant."
"It's active learning, it's learning through first hand experience and it's much more meaningful to children," she said.
But Iwan Guy, the acting director of the headteachers' union NAHT Cymru said a lack of funding meant Wales was in danger of having a "mix and match system".
"We thoroughly endorse the foundation phase but it has to be implemented with the full resources we were promised."
"There's an expectation that schools will deliver a Rolls-Royce system but they're only prepared to fund us for a small family saloon."
"Frankly it's not good enough for the children of Wales."
"I give credit to Jane Hutt. She has been listening. We do not hold Jane Hutt responsible for the situation we are in," he added.
The shadow education minister Andrew Davies AM said the Welsh Conservatives were "fully supportive" of the scheme but warned the assembly government not to be complacent.
They are far far more relaxed and happy and I think the staff would say they are as well.
Alison Matthias, Ysgol Emmanuel
"The full roll-out of the foundation phase has been delayed because the assembly government got its sums wrong," he said.
"This has caused a great deal of uncertainty and disruption for parents, pupils and teachers."
The new early years curriculum has already been trialled at over 80 schools, nurseries and playgroups around Wales.
Nursery and reception pupils at Ysgol Emmanuel in Rhyl have been following the new scheme since last September.
The school's deputy head teacher, Alison Matthias, said she was pleased with the children's progress.
"They are far far more relaxed and happy and I think the staff would say they are as well."
"You've got to realise, as with everything else, you have to be prepared for the tears as well as the smiles."
But she added it was important to make sure that children learned all the required skills.
"I was very vocal in saying if our standards go down we are stopping this, but in fact our standards didn't go down, they went up," she added.
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