Most teachers say subject choices for pupils in S4 have narrowed, with staffing levels given as the most frequent reason.
A survey by the Scottish Parliament's Education and Skills Committee found that 82 per cent of staff said subject choices for that year had reduced.
Committee papers revealed that, out of 500 responses to the survey, "aspects of staffing were mentioned nearly 350 times by respondents", even though this was "not a theme suggested through the question wording".
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The next most common reason cited by teachers was timetabling, which was mentioned 162 times.
'Not enough teachers'
In their responses, staff complained that some subject choices were "affected by the availability of specialist teachers", while others said that "there are not enough teachers at the school to deliver the courses required".
One teacher stated: "The availability of staff is the driver for deciding the entire curriculum. Our curriculum breadth and depth has been eroded recently due to the need to cut back on staff."
MSPs on the Education and Skills Committee have been examining the issue amid concerns that youngsters are not able to study as many different subjects in the senior phase of secondary school.
Youngsters often used to study up to eight subjects in S3 and S4 under the old Standard Grade system, but following the introduction of National 4 and 5 courses in 2013-14, many schools now only offer students the chance to study six subjects.
Some educationalists, however, say that it can be misleading to compare the new and old systems, and that the number of qualifications accrued over the entirety of the “senior phase” – from S4-6 – is what matters now.