Education directors, headteachers and teachers have mounted a scathing attack on the implementation of A Curriculum for Excellence, claiming it lacks clarity, cohesion, leadership and resources - charges which the Government has vigorously rejected.
A spokesman for primary heads likened the development to the fairy tale The Emperor's New Clothes.
Larry Flanagan, education convener of the Educational Institute of Scotland, called it "the least resourced curriculum development I have ever experienced", although it was billed as "the most fundamental curriculum development ever".
And David Cameron, vice-president of the Association of Directors of Education in Scotland, said the initiative required more decisiveness and leadership. He called for a shake-up of its management board, of which he is a member.
All three groups told MSPs on the parliamentary education committee that development of the new curriculum risked losing momentum unless its contents were fleshed out.
They have also warned that teachers and parents do not feel involved in the development and that there have been delays in disseminating information about it.
A government spokeswoman said changes to qualifications to reflect the new curriculum would be announced in late spring. As for communication about the curriculum, she said: "Directors of education and headteachers have a critical role in communicating to teachers and parents, and we would be concerned if this was not already happening."
The Government made no apologies for allowing schools, authorities and teachers time to reflect on the new curriculum, she said, but the information flow had now increased and almost all of the draft guidance had been released within a few months' time.
The spokeswoman refuted Mr Flanagan's claims about resources, insisting that funds had been given to local authorities to familiarise staff with the changes. She added: "Government recognises that there will be a need to kick-start ACfE with support material and engage wider Scotland in supporting this.
"But a balance has to be struck between offering everything on a plate and giving space for teachers to generate their own lessons."
Mr Cameron acknowledged to the parliamentary committee that he had to bear some responsibility for the vacuum - but he was a lone voice on the curriculum management board, which was largely made up of officials who were not in a position to take the lead.
The other members were civil servants, who had to be conscious of the position likely to be adopted by the Education Secretary; members of HMIE, who could not be seen to be "inspecting their own advice"; and officials from the Scottish Qualifications Authority and Learning and Teaching Scotland.
Brian Cooklin, president of the Headteachers' Association of Scotland, said: "It needs clear leadership. Who's in charge? No one knows. There are a number of agencies doing different jobs, but no national direction or leadership in terms of a communications strategy."
Neither time nor resources had been given for teachers to examine the changes, he said. "It's coming to you from the ether - you just feel it, but there's no time to discuss it."
Teachers want to know what it is going to look like and how they are going to timetable it. People are past the stage of wanting "bland assertions and statements", he said.
Mr Cooklin also warned that the current round of efficiency savings would damage delivery of the new curriculum because, with fewer staff and cuts to management time and structure, schools would lack the capacity to implement it.
The "vacuum" in national leadership meant that individual schools and local authorities were developing their own schemes under the badge of A Curriculum for Excellence, Mr Cooklin said. "Given the large number of children who move around the country every year, this presents an added problem."
Referring to The Emperor's New Clothes, Gordon Smith, past president of the Association of Headteachers and Deputes in Scotland, said: "ACfE has a fantastic philosophy but, at the end of the day, what are we actually wearing?"
The lack of clarity was illustrated by the terminology used, he said. "I wonder why the first two stages are still called 'early' and then 'stage 1'? Why not call the pre-5 bit 'stage 1'?"
Leader, page 22.