Mary Curnock Cook, chief executive of the Universities and Colleges Admissions Service (Ucas), writes:

Everyone wants to know what the new “normal” sixth-form curriculum will look like for students taking A-levels in England, where linear A-levels are being taught in some subjects from this academic year. 

Universities want to know so that they can frame their entry requirements for 2017 admissions. Schools and colleges want to know so that they do not find themselves swimming against the tide and potentially disadvantaging their students. And Ucas wants to know because everyone expects us to offer accurate and timely advice to university applicants.

The key question is about whether to offer the now optional AS examinations at the end of Year 12, given that these will no longer count towards the final A-level grade.

If we fast-forward two years to a time when all A-levels will be reformed and linear - that is, A-levels being taught from autumn 2017- the question is slightly less complicated. With all A-levels (in England) being in the same format, school leaders will need to assess the relative merits of remaining assessment-free in Year 12 against the benefits of the mid-course assessment in terms of a formal progress check, motivation and curriculum breadth.

Those that eschew the AS exams in Year 12 could expect to gain approximately half a term of teaching and learning. They will also give themselves wider options regarding how they organise teaching of the A-level syllabus.

There now seems to be broad consensus that the AS is less than half an A-level, but the examination takes place halfway through the timeline. Without the AS exam, schools could rearrange the curriculum with a single end point in view, at the end of the course, and this could have huge advantages. For example, delivery of the syllabus could be flexed to deliver all poetry together, or all mechanics together, rather than progressing through all sections of the syllabus in parallel. And larger sixth forms could be streamed, offering different curriculum designs depending on ability.

Undoubtedly, the linear model presents some opportunities that have had relatively little airing thus far. But the downside of going all-in on linear is that schools and pupils will either have to start three A-levels and finish those same three, two years later, or they will have to start four A-levels and potentially drop one of them halfway through with nothing to show after a year of study. 

I can’t imagine many pupils being highly motivated to study for an exam in their weakest subject when it takes them out of their stronger subjects for a period of revision and examination time.

Those that elect to continue offering AS exams in Year 12 will lose the extra curriculum time but regain the flexibility of starting with four (or even five) A-levels and dropping one after receiving AS results in all subjects. 

This broadening of the curriculum and the chance for pupils to try out new subjects without penalty was one of the standout successes of the Curriculum 2000 changes that ushered in the AS/A2 format. Continuing to offer the AS will also retain the motivational stepping stone for less confident learners that can inspire them to start thinking about progression to higher education.

The majority of students who would, I fear, simply revert to the pre-2000, three A-level curriculum, might experience worse outcomes simply from making the wrong choices of subjects. At least some of the perceived grade inflation post-2000 must have been attributable to the format that allowed students to choose four subjects but to pursue only their three strongest through to the full A-level.

But these are decisions that experienced educators are better qualified to make than I am - and they will make them based on the profile of their own sixth-formers and their own judgements about what will work best in their circumstances.

So, challenging decisions to make for 2017. But what of 2015 when the majority of schools are managing a mixture of reformed and old A-level subjects? It seems to me to be impossible for schools to manage any kind of exam-free zone in Year 12 - which means that it will be impossible to manage any real benefit of extra teaching and learning time in the summer term, with the likelihood that there will be some students needing to be freed up to take AS exams in every class.

For this reason, I imagine that most schools will elect to continue with AS examinations in all subjects, at least until 2017. This appears to be a manageable option in the short term, and it has the added benefit of allowing teachers to get used to the new-style A-level syllabuses and assessments with relatively low risk. I doubt the regulators will want to preside over any dramatic divergence in the national results profile for reformed subjects.

My logic is not, however, entirely borne out in Ucas’ recent survey to find out what decisions schools and colleges have made about the key stage 5 curriculum for this year and next. Only two-thirds of respondents said they would participate in AS exams in reformed subjects in 2015, with a worrying one in six schools saying they still haven’t decided what to do. The 16 per cent who said they definitely wouldn’t be offering the AS exams were mostly independent schools.

Perhaps schools that are still anxious about what is the right thing to do will be comforted by the early indications from universities such as UCL, Aston and Sheffield, which have been quick to confirm that their ever-professional admissions officers have updated their policies to ensure that no applicant will be disadvantaged whether they apply with or without AS results. 

That the survey paints a picture of continuing indecision about what to offer from 2017 is slightly less worrying. I am confident that, with one full cycle under their belts, and a set of results that broadly meet expectations, teachers will quickly assimilate their growing familiarity with the new A-levels and use their professional expertise to make decisions that support the best outcomes for their students.