Some pupils count accurately but still struggle to judge relative size, recognise useful groups or estimate a plausible amount.

Keep the support tied to current number teaching rather than a separate visual game.

Use a familiar benchmark

Choose a reference quantity pupils know, such as five, ten, one hundred or a relevant measurement. Compare a new quantity with that benchmark before finding the exact value.

For primary pupils, use structured objects, dot patterns or ten frames. Ask whether the quantity is more, less or approximately the same, then count to check.

For secondary pupils, use reference values connected to the topic, such as 50%, one metre, 0.5 or a known scale interval. Ask for an estimate before calculation or exact reading.

Listen to the reasoning

Notice whether pupils:

• count every item when a structure is visible;

• fail to use known groups;

• give implausible estimates;

• confuse a larger numeral with a larger quantity;

• change their judgement after seeing the exact value.

Ask how the benchmark helped and how much larger or smaller the new quantity appears.

Link estimate and exact value

The estimate should inform checking, not replace calculation. After finding the exact value, compare it with the original judgement and discuss any large difference.

Reduce support

Vary the benchmark and representation as pupils develop more secure magnitude judgements. Persistent difficulty across quantities and representations may require structured number-sense assessment and provision.

Further guidance

• NCETM's primary teacher guides on number are free to download. The segments on comparing quantities and composing numbers to 10 and 100 were written for Years 1 to 3, but their representations suit older pupils who need to revisit these ideas.

• NCETM's free KS3 Checkpoints include an “Estimation and rounding” deck of short activities for checking whether pupils judge size sensibly.

Talamo has no commercial relationship with any of the organisations named here. We suggest them only because we think they could be useful to schools.