NSW education leaders are concerned an "incoherent" HSC mathematics syllabus "riddled with mistakes" has been rushed through by the Board of Studies before its transition to the NSW Education Standards Authority.

The draft syllabus was savaged as a "cut and paste disaster" by Sydney Grammar's former master of mathematics Bill Pender, and described as "appalling" by SCEGGS Darlinghurst principal Jenny Allum when it was released for consultation last year.

The Board of Studies, which endorsed an updated version of the syllabus in December, became the NSW Education Standards Authority on January 1.

A spokeswoman said the authority was still completing edits on an "open timeline" following a review led by Professor John Mack from the University of Sydney's School of Mathematics and Statistics.

Ms Allum said she was approached by a Board of Studies inspector in December after her concerns were made public to review changes made to the final syllabus.

She said she was told she would not be able to share the revised syllabus with her colleagues.

"Why?" asked Ms Allum. "These are not state secrets, or matters of personal privacy or commercial-in-confidence. They are mathematics syllabuses for school students, for goodness sake."

Ms Allum, a former manager of curriculum at the Board of Studies, said the approach had been made with the intention of keeping her quiet.

"That's a great way to shut me up and stop me from talking to the media," she said.

A spokeswoman for the NSW Education Standards Authority said it was standard protocol for NSW syllabuses to be kept confidential until formal release by NESA.

"It followed an extensive and established process, involving consultation with more than more than 1300 teachers, students, professional associations, industry representatives and academics [since August 2014]," the spokeswoman said.

The draft syllabus included an increase in the number of take-home projects and the introduction of statistics, as well as adjustments to the way the demands for proof, Euclidean and co-ordinate geometry are taught.

The NESA spokeswoman said the recent results of students in the Program for International Student Assessment (PISA) and Trends in International Mathematics and Science Study (TIMSS), suggested the application of maths to real world problems is an area where NSW students needed to improve.

Ms Allum said the changes would affect rural teachers who relied more on the syllabus than their counterparts in the city.

"Kids are getting cheated out of the best possible education that they can," she said.

In October, Dr Pender and the head of the School of Mathematical and Physical Sciences at UTS, Anthony Dooley, warned that the board was in danger of losing its credibility as the authority responsible for mathematics education in NSW under the proposed changes.

"It has taken NSW 30 years to get it to this kind of level and this sets us back several paces," said Professor Dooley.

The Mathematical Association of NSW was critical of the lack of clarity in parts of the syllabus but applauded many positive features during its consultation with the board.

"MANSW believes the syllabus development process is transparent and well consulted," President John Meng said in October.

NESA is set to release the new HSC syllabuses for English, mathematics, science and history this year. They will form the basis for 2019 HSC exams.