Pressure is growing on the Scottish Government to revisit its limit of five subjects to be studied in S4 under the revised exams structure.
The General Teaching Council for Scotland is the latest body to express reservations about early specialisation and inappropriate subject choices if pupils can opt for no more than five subjects in S4. There should be "a safety net for pupils who make inappropriate choices", it says.
The council was responding to the Government's consultation on the "next generation" of qualifications replacing Standard grade and Intermediate 1 and 2.
On behalf of the GTCS, Tony Finn, its chief executive, concedes that a five-subject limit might have the advantage of promoting greater depth of knowledge in subject areas, but counsels that this would have to be built on "successful, and preferably accredited, achievement at age 15".
He warns: "Pupil learning and experience in S2 remains an issue which is not addressed in this consultation. For many pupils, the curriculum in S2 lacks focus and motivation. Progression across the curriculum is required from S1-3."
Mr Finn says the council also wants an alternative to the proposal to combine internally-assessed units and an external exam for the new S4 qualification.
While the Government has opened up a debate on whether the units should be graded A-C or simply assessed on a passfail basis, the GTCS makes a more radical suggestion - grant a C pass to students who have passed all internal units. More able students, it suggests, could then move straight to a higher level, while others could sit an external exam if they wanted to gain a pass higher than C.
This would provide teachers with the ongoing "summative" knowledge they require on pupils' performance to feed into their final "formative" assessments, it asserts. But the GTCS acknowledges such a system would probably need an increase in external moderation as a check on the validity and reliability of test scores.
The council also urges further consideration of how levels 1, 2 and 3 covering primary to early secondary should be assessed, particularly in the use of formative approaches and the recording of standards.
A "credible" statement of achievements at the end of S3 needs to be developed, it adds.
The GTCS calls for further guidance on whether maths and English should feature as a required, or desired, part of the senior group of subjects chosen from S4 onwards; on how literacy should be defined; and on the means of tracking pupil progress across all levels.