Pass rates for national qualifications have hit new highs over the past two years, and this year, the rise in the proportion of entries attaining an A grade was headline news.

But with the planned return of national exams in 2022, Scottish headteachers are concerned that senior students could be disadvantaged if pass rates nosedive and return to pre-pandemic levels - or, conversely, that the qualifications gained in the past two years could be devalued.

As a result, heads are calling for students sitting exams in 2022 to receive the grade their work merits - and for Scotland’s exam body not to “interfere” with grading.

Traditionally, after students sit their exams, meetings about grade boundaries are held and the marks needed to attain the different grades are adjusted, depending on how demanding the papers are deemed to be.

For example, in 2015, the Scottish Qualifications Authority (SQA) admitted that the new Higher maths exam was harder than anticipated, so to get a C grade that year candidates needed 34 per cent, compared with the previous year’s 45 per cent.

But grade boundaries can also be adjusted in the opposite direction, meaning that students need to get more marks in order to pass.

This year, School Leaders Scotland (SLS) is making the case for a more hands-off approach so that students experience “a level playing field” and are not disadvantaged by the reintroduction of external exams.

Will this year’s exam students be disadvantaged?

Jim Thewliss, general secretary of SLS, believes that the solution is to “grade on the basis of the evidence” and not to “interfere” and adjust grade boundaries, whether this year’s results are based on exams or teacher judgement.

“In a typical year, all the results are looked at in the round and the grade points are adjusted,” he says. “This year, that particular exercise did not take place and the grades were awarded based on the individual performance of the young people.

“We would be happier going forward if that continued; we think it would be fairer.”

In 2019, the last time national examinations took place in Scotland, the Higher pass rate was 74.8 per cent; in 2020, it was 89.3 per cent and in 2021, it was 87.3 per cent.

This year, the proportion of students gaining A grades also rose: at Higher, 47.6 per cent of entries gained the top mark, up from 40 per cent in 2020 and 28.5 per cent in 2019.

Speaking anonymously to Tes Scotland in the wake of this summer’s results, one head questioned whether the “inflation” of the past two years would be retained, adding: “If we don’t then it’s unfair on the 2022 cohort when they compete for jobs and further education.”

Another head pointed out that, if SQA results are considerably lower in 2022, that could “reduce confidence in the awards gained in those two [previous] years”.

The SQA says in A Guide to Setting Grade Boundaries that these changes to the marks required to attain a particular grade are about taking account of issues such as changes to the length of exams, or feedback from examiners or markers about “the demand of the assessment”, and that there is “no fixed proportion of grades” - so no ceiling on the proportion of candidates who can get an A, B, C or D.

However, Maureen McKenna, the education lead for Scotland’s biggest local authority, Glasgow City Council, recently suggested in an interview that the SQA “norm references” pass marks.

McKenna told The Herald newspaper that schools have “fluctuations in grades because you will have good cohorts of young people and, sometimes, not-so-good cohorts of young people”.

Yet, before 2020, she pointed out that for National 5 maths, regardless of how many people were presented, 67 to 68 per cent got an A to C grade.

She suggested that this was because the “SQA norm references the pass mark so it’s always about two-thirds or so that pass”.

In response, SQA chief executive Fiona Robertson said: “We don’t norm reference pass rates in Scotland, as Maureen suggests.”

Yet headteachers obviously believe that if the SQA steps back, the pass rate is less likely to plummet in 2022.

For its part, the SQA says that whether grade boundaries are adjusted is “an issue that still requires detailed discussion across the education system” and that “SLS and many others will have an important voice in that discussion”.

The SQA adds that “credibility and fairness will underpin final decisions as they do every year” and that the modifications to assessment already in place are “designed to take account of disruption to learning and to deliver fairness to learners”.

Emma Seith is a reporter at Tes Scotland. She tweets @Emma_Seith