The Scottish Government's head of education has admitted the change- over to the new curriculum, due next year, had to be just right and "we are not there yet".
Philip Rycroft, director general for education and lifelong learning, told the conference of 250 secondary heads that Government action over the next few months - on the final curriculum guidance and qualifications framework - would be critical to the programme's success.
"We are at an important swivel-point just now," he said.
The outcomes and experiences for all subject areas will be published on April 2, and the Government will launch its assessment and qualifications framework in the summer.
Against a backdrop of head-teachers' concerns about assessment, lack of clarity, tight timescales and scarce resources, the Education Secretary and her officials sought to reassure their audience that they were in listening mode.
But tension remained between Fiona Hyslop's insistence that teachers must show the professional independence they had been demanding for years, and the profession's insistence that until it knows the detail of the new qualifications and assessment system, it cannot decide what it should teach in S1-3 in a year's time.
Ms Hyslop told the Glasgow conference: "Teaching is a four-year degree profession for a reason and part of that is the ownership it gives teachers. If they can't take the steps forward, then there might be questions as to why it is a degree programme. In medicine or law, they don't ask for a route-map."
The Scottish Qualifications Authority's chief executive, Janet Brown, promised that the context, skills and content of the new qualifications would match the CfE outcomes and experiences, but the exams authority would be led by the CfE management board.
The SQA was looking at how it carried out assessment in the college sector, to see if that provided a useful model for "measuring what is valuable" in schools.
Headteachers' concerns were summed up by David Chalmers, head of Biggar High, South Lanarkshire: "We are afraid, and our teachers are afraid, that we will build a new system and provide better experiences for youngsters in S1-3 - and then we will suddenly be faced with the same old exam system and we and our teachers will be found wanting."
David Cameron, president of the Association of Directors of Education in Scotland, warned that CfE would "fall apart like a house of cards" if the assessment system did not reward the style of teaching demanded by it.
Larry Flanagan, education convener of the Educational Institute of Scotland, concurred: "If there is one single issue that brings down the whole system, it will be the assessment arrangements."
Full report 4, Leader 22.