If a primary mathematics teacher wants to design lessons that ensure both…

Concept: Mathematics content can be planned around different organising units. A conceptual field is the whole network of situations, problems, operations and representations that one mathematical idea spans — for example, all the joining, separating, comparing and missing-part situations that together give meaning to addition and subtraction. Planning by conceptual fields makes the idea, together with every situation that gives it meaning, the unit of the lesson sequence.

Application: The stem sets two demands at once: the prescribed content must be covered, and the ideas must be understood deeply. Every syllabus topic sits inside some conceptual field, so a sequence built field by field still passes through the whole prescribed content, and coverage is preserved. Because a field is taught through its full range of situations and representations — concrete material, pictures, the number line, symbols and word problems — the same lessons build meaning rather than fluency alone. A single organising unit therefore carries both demands.

Cross-check: Test each organising unit against the two demands the stem states:

Only one organising unit satisfies both columns, so the approach a primary mathematics teacher should prioritise is planning around conceptual fields.