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What do Core and Extended mean?

Two papers for the same subject, a grade ceiling on one of them, and a decision made months before the exam.

Some Cambridge IGCSE subjects are set at two levels. Core covers the main content of the syllabus. Extended covers the same content plus a supplement, and is examined on harder papers. It is one subject with two routes through it, not two subjects.

Which subjects are tiered

Fewer than people assume. Mathematics is tiered, and so are Biology, Chemistry, Physics, Combined Science and Co-ordinated Sciences.

Several subjects families ask about are not tiered at all: First Language English, English as a Second Language, Literature in English, Economics, Business and Accounting are single-tier, and every candidate sits the same papers. If someone says a student is "in the lower set" for one of those, that is a class grouping inside the school, not a different entry.

The part that matters: the ceiling

Core papers are capped. A student entered for Core cannot be awarded a grade above C, however well the paper is answered — the marks above that simply do not exist on the paper. Extended papers reach A*. The exact bottom of the Extended range differs between syllabuses, so the grade range printed in the syllabus itself is the one to trust.

The papers differ too, not just the questions on them. In the sciences, for example, Core candidates sit the Core multiple-choice paper and the Core theory paper; Extended candidates sit the Extended versions of both. The practical component is the same either way.

Who decides, and when

Teachers decide, subject by subject, and the decision is made at entry — months before the exam, not on the day. A student can be Extended in one subject and Core in another; there is no rule that the tier has to match across a timetable.

Both directions carry a cost. Entering a capable student for Core hands them a ceiling they cannot break through. Entering a struggling student for Extended, on a syllabus whose supplement they have not covered, risks a lower grade than Core would have produced. This is a judgement about one student on one syllabus, which is why it belongs to the teacher who has seen the work.

What to ask, and by when

  • Which tier is this student entered for, in each tiered subject?
  • What would have to change for the entry to move to Extended?
  • When does the entry deadline fall? After it closes, the tier is fixed for that series.

The Edexcel equivalent

Pearson Edexcel uses Foundation and Higher rather than Core and Extended, and the same logic applies: in Mathematics A, Foundation targets grades 5 to 1 and Higher targets 9 to 4, with a grade 3 available just below. The names differ; the ceiling does not.

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