Geometry – Properties of Shape
Geometry in Year 1 isn't about spotting a shape by eye — it's about proving what you see with the right vocabulary. Every mark scheme here rewards precision: '4 cm equals 4 cm, so two sides match' beats 'it looks isosceles' every single time. Learn the definitions cold, and the describe/explain questions answer themselves.
Overview
This topic builds the vocabulary that every later geometry unit depends on — Pythagoras, transformations, and trigonometry all assume you can already classify a triangle, name a circle's parts, and justify an angle using a rule rather than a protractor guess. The exam questions almost never ask you to just calculate; they ask you to describe or explain, which means naming the property and quoting the evidence for it.
- Triangles and polygons: classification by sides and angles, plus interior angle sum rules.
- Symmetry and tessellation: how shapes reflect, rotate, and tile a plane with no gaps.
- Congruence and similarity: same shape same size vs same shape different size — and how to prove either.
- Circle properties: the vocabulary (radius, chord, tangent, sector...) that every circle question is built from.
- Angle rules: the small set of 180°/360° facts that justify almost every angle calculation you'll ever do.
- Lines and angles: what happens when a line crosses two parallel lines — corresponding, alternate, co-interior.
The shape of the chapter
Command terms that drive this topic
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| Identify / Name | State the single correct classification word — no working needed. | Knowing | 1 mark for the exact term (e.g. 'isosceles'); a description here earns nothing extra. |
| Describe | State the specific property AND connect it to the given numbers/diagram. | Knowing & Understanding | Usually 1–2 marks: one for the rule, one for linking it to the actual values given. |
| Explain | Give a reason that shows WHY, using a geometric fact (angle sum, side equality, parallel lines). | Understanding | Bare assertion without the underlying rule caps the mark. |
| Calculate | Show the numeric working, not just the final number. | Applying | Method marks are awarded for the correct equation set up, even if arithmetic slips. |
| Give an example of | Produce your own valid instance that satisfies the rule. | Applying | Mark lost if your invented numbers don't actually satisfy the underlying rule (e.g. angles not summing to 180°). |
| Compare | State a similarity AND a difference between two things. | Understanding | One-sided answers (only similarity, or only difference) lose half the marks available. |
Key point
Overview