Leading headteachers have criticised the quality of guidance being issued to schools on the new National qualifications, calling it "inconsistent" and claiming that it provides teachers with sloppily presented examples, complete with spelling mistakes.
They also hit out at the number of last-minute changes to the qualifications, which they said had left teachers feeling "insecure" and "uncertain".
Ronnie Summers, outgoing president of School Leaders Scotland, told the organisation's annual conference this week that leaders had had to push for "clear and timeous" guidance from the Scottish Qualifications Authority on the new exams and draw attention to "inconsistencies of message". This year - the first of the new qualifications - would be the most demanding in the implementation of Curriculum for Excellence, Mr Summers told the SLS conference.
The quality of assessment examples being issued by the SQA was also failing to inspire confidence, the organisation's incoming president, Caroline Amos, told TESS.
The headteacher, who has led Paisley Grammar in Renfrewshire for the past seven years, said that these did not follow a set format and even contained spelling mistakes.
"They (the SQA) are just issuing examples of assessment on their website in the same way as they receive them from schools," Ms Amos said. "They are not tidied up or in the same sort of format as the ones that come from the SQA."
The incoming SLS president added that there had been too many last-minute changes to the Nationals, which had made teachers feel "insecure" and "uncertain". She made a plea for an end to "midstream changes" when it came to the introduction of the new Highers next year.
Ms Amos will also make a commitment in her address to conference today to keep pushing for clear guidance and support for schools on the new qualifications from the SQA and Education Scotland. This, she is expected to say, "will help school leaders to answer the questions that teachers are asking".
Ms Amos said: "It's about giving people that sense of security that what they start with is what they will be finishing with.
"There have been a number of changes in subject areas in the course of this session. Changes to maths, for instance, came out in the past couple of weeks.
"Teachers want to be sure that they are delivering the right thing, getting assessments right and saying the right thing to kids. What we don't want is there to be midstream changes to the Higher."
On a positive note, she added that lessons in Scottish schools were "more challenging, motivating and interesting" and teachers "more highly skilled" than ever thanks to CfE.
The new National qualifications, which placed more emphasis on coursework than the old Standard grades, were harder, she said. "Children in S4 with older brothers and sisters feel that they are doing more and working harder," Ms Amos argued. "That's no bad thing. My sense is that there is more demand and challenge on S4 at the moment.
"There is still a lot of what was good from before, but we now have more highly skilled professionals teaching children. Curriculum for Excellence has made us question what we are doing, why we are doing it and how."
The SQA, however, rejected the criticism of its guidance, saying that changes made to course guidelines had come about as a result of feedback from the teaching profession.
Gill Stewart, SQA's director of qualifications development, said: "SQA sees the implementation of new qualifications as a partnership and recognises the need to listen to its partners and to be flexible and responsive at all times. The changes to maths were made specifically as a result of feedback from stakeholders."
She added: "SQA will continue to listen to, work with and support the teaching profession to ensure that the Nationals are introduced successfully, to the benefit of Scotland and its young people."
As to whether or not the new qualifications were more difficult, Dr Stewart conceded that they could be seen by some as representing "a greater degree of challenge".
She said: "The new qualifications require pupils to apply and interpret the knowledge and understanding they have gained and demonstrate the skills that they have learned.
"This might be seen by some as representing a greater degree of challenge. However, the aim is to better prepare young people for the modern world of work and to ensure that they are leaving school with a broader range of relevant skills."