The HAS has protested to the Scottish Qualifications Authority that the first paper contained an "unacceptable level of difficulty". Some questions were "vague and confusing, badly worded and obscure and bore no resemblance to the SQA specimen paper".
The association claimed many pupils were "clearly distressed and demoralise", and had to be persuaded to return to sit the next paper.
Its statement added that the pupils had been well prepared by their teachers for the first exam under the Higher Still programme. "They were badly let down by the SQA who produced a paper which was unfair. Mathematics teachers who worked so hard to make Higher Still a success have been left deflated and at a loss to know what is required of them."
A report from the SQA is expected within a month.