How can you tell they’ve got it: Regular and irregular polygons?

If they’ve got it, you’ll see things like: Classify a set of polygons as regular or irregular; Explain that a regular pentagon has 5 equal sides and 5 equal angles; Identify that a rectangle is irregular (equal angles but not all equal sides) unless it is a square. Or just try it together: If you show your child a stop sign (regular octagon) and a wonky eight-sided shape, can they explain which is regular and which is irregular — and why?

Mathematics Geometry Ages 9–10

Regular and irregular polygons

Your child can tell regular shapes from irregular ones. A regular shape has equal sides and equal angles, like a stop sign.

In curriculum terms

Distinguish between regular and irregular polygons based on reasoning about equal sides and equal angles

Ages are typical, not deadlines — follow your child’s pace. How to help at home →

How to tell they’ve got it

Tick these off as you see them — no test required.

Classify a set of polygons as regular or irregular
Explain that a regular pentagon has 5 equal sides and 5 equal angles
Identify that a rectangle is irregular (equal angles but not all equal sides) unless it is a square

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Try this together

If you show your child a stop sign (regular octagon) and a wonky eight-sided shape, can they explain which is regular and which is irregular — and why?

Where this sits on the map

Stuck here? Check the skills it builds on first. Confident? Here’s what it unlocks.

Builds on

Understanding anglesages 8–9Shape classification supports distinguishing regular from irregular

Estimating Anglesages 9–10Classifying regular/irregular polygons benefits from angle estimation skills

Regular and irregular polygonsthis skill · ages 9–10

Unlocks

Classifying shapes by propertiesages 10–11Hierarchy includes regular/irregular distinction from Y5

Types of anglesages 11–13Describing regular polygons requires knowing the distinction from KS2

Precise Maths Vocabularyages 9–10Regular/irregular polygon vocabulary exercises geometric precision

2-D shapesages 10–11Drawing regular/irregular polygons benefits from property knowledge

solid = must come firstdashed = helps

Curriculum alignment

Where this fits in the official school curriculum — our best automated guess, not yet checked by a person.

Show candidate curriculum codes · 1 ACARA · 2 NSW · 1 VIC

Australian Curriculum v9 candidate

AC9M5M02medium confidenceYear 5 · Measurement

solve practical problems involving the perimeter and area of regular and irregular shapes using appropriate metric units

NSW syllabus codes & stages only

MA2-GM-03medium confidenceMathematics K-10 · Stage 2

MA3-2DS-01low confidenceMathematics K-10 · Stage 3

Victorian Curriculum 2.0 codes & levels only

VC2M5M02low confidenceMathematics · Level 5 · Measurement strand

These are candidate alignments generated by semantic matching — machine-suggested and unreviewed (v0.1), not official or verified mappings. For official curriculum content see australiancurriculum.edu.au, curriculum.nsw.edu.au and f10.vcaa.vic.edu.au. Don’t rely on them for registration or compliance purposes.

Nearby on the map

3-D shapesages 9–10 Angle Sum Rulesages 9–10 Classifying shapes by line propertiesages 9–10 Degrees and turnsages 9–10

All Geometry skills →