there should be more adult-guided work and less free play in the new foundation phase for three to five-year-olds, it was suggested this week.
The advice comes after the quality of literacy, communication and language teaching in pilot schools was reported to have "significantly declined"
this year compared with 2005.
But there were counter-claims that the team evaluating the new scheme had not taken evidence from enough classes.
And there was unease about plans to increase the adult:child ratio for three to five-year-olds, at a conference this week in Cardiff to launch an evaluation report on the pilot scheme's second year.
The ratio would increase from 1:8 to 1:10 for classes under the control of a qualified teacher. An action plan detailing plans for a huge training programme was also released.
Professor Iram Siraj-Blatchford, co-author of the latest evaluation report, said stunning practice in the foundation phase had been observed across Wales. She told conference delegates that a call for more adult guidance, contained in one of 12 new recommendations, did not mean a return to overly formal desk-based teaching.
The recommendation concludes that a decline in children's opportunities for literacy learning and interaction with teaching staff means these areas should be given more priority.
But Professor Siraj-Blatchford, who last month was appointed to the minister's advisory board of experts, said teacher support for the foundation phase remained high at more than 80 per cent - although down slightly on 2005.
Parents support the initiative too, but are also concerned about the balance between play and more structured learning, she said.
However, one teacher at the conference, said: "How far should adult guidance go before we go back to where we were before?"
And Selwyn Jones, secretary of the Welsh Primary Schools Assocation, said some members had complained about a lack of evidence. "There is a feeling that two visits is not enough to make a valid judgement on," he said.
As part of this year's evaluation, observers have looked at teaching practice at each pilot setting twice, as well as interviewing teachers, parents and other stakeholders.
Teaching provision was graded one (poor) to seven (excellent) using a system called the early childhood environment ratings.
The report also recommended improving the currently "poor communication"
with key stakeholders, and ensuring qualified teachers are involved in all settings by a certain deadline.
Announcing the action plan, Jane Davidson, minister for education, lifelong learning and skills, said she would delay estimating how many extra staff would be needed until data was returned from local authorities.
In September, figures revealed that more than half of Wales's primary schools do not yet have enough people to deliver the foundation phase.
The statutory roll-out of the foundation phase begins in September 2008, with completion by July 2011. It has been piloted in 41 playgroups, nurseries and infant primary schools across Wales.
Ms Davidson said the initiative was not not just about play, but also provided more appropriate and relevant opportunities for children to learn and develop.
"Play that is well planned helps them to think and make sense of the world," she said.
* Monitoring and evaluation of the effective implementation of the foundation phase, see new.wales.gov.uk