Geometry is often under-practised compared to number work, yet it accounts for a steady 15–20% of the marks on most 11+ maths papers. The good news for parents is that geometry rewards a small set of memorised facts more than raw arithmetic speed, so a child who learns the rules and practises applying them can bank marks quickly. This guide walks through every geometry sub-skill the current GL Assessment-style 11+ tests, with worked examples, a quick-reference formula box and the exact traps that lose children marks under time pressure.
How geometry appears in the real exam
Since CEM's separate 11+ tests were phased out around 2022–2023, GL Assessment now sets the maths for most selective regions, with the Essex CSSE consortium and independent-school ISEB papers as the main alternatives. A GL maths paper is typically around 50 questions in 50 minutes — roughly a minute a question — multiple-choice with answers A–E marked on a separate OMR answer sheet, and no calculator. Geometry questions cluster around angles, area and perimeter, properties of shapes and coordinates. Probability and more open geometry proofs are rarer in GL but appear more often in CSSE and independent papers, so check your target format on our 11+ process guide.
Angle facts every child must memorise
Most 11+ angle questions are solved by combining two or three basic facts. Learn these five cold and a large share of the geometry section becomes routine.
| Rule | Angle total |
|---|---|
| Angles on a straight line | 180° |
| Angles around a point | 360° |
| Angles in a triangle | 180° |
| Angles in a quadrilateral | 360° |
| Vertically opposite angles | Equal |
Worked example: a triangle has angles of 65° and 48°. The third angle is 180 − 65 − 48 = 67°. If that same triangle sits on a straight line, the exterior angle next to the 67° is 180 − 67 = 113°. Build answers step by step rather than guessing, and remember diagrams in the 11+ are usually not drawn to scale, so never measure with a ruler — calculate.
Properties of 2D and 3D shapes
Expect questions on sides, symmetry, parallel edges and right angles. Know the regular polygons up to the octagon, and be secure on the four special quadrilaterals: square, rectangle, parallelogram and rhombus differ in their sides, angles and lines of symmetry. For triangles, learn equilateral (all sides and angles equal, three lines of symmetry), isosceles (two equal sides, one line of symmetry) and scalene (all different).
- Lines of symmetry: a square has 4, a rectangle 2, an equilateral triangle 3, a regular hexagon 6.
- 3D solids: a cube has 6 faces, 12 edges and 8 vertices; a cuboid the same counts. A square-based pyramid has 5 faces, 8 edges, 5 vertices.
- Nets: practise spotting which flat net folds into a cube — a classic GL question. Only certain arrangements of six squares work, so visualise folding before you answer.
Perimeter, area and volume — the formula box
Children mix up area and perimeter constantly, so anchor the difference: perimeter is the distance around the outside (add all the sides), while area is the space inside. Keep this quick-reference box in your child's revision folder.
| Measure | Formula |
|---|---|
| Perimeter of a rectangle | 2 × (length + width) |
| Area of a rectangle | length × width |
| Area of a triangle | ½ × base × height |
| Volume of a cuboid | length × width × height |
Remember that area is measured in square units (cm²) and volume in cubic units (cm³) — forgetting the correct unit is a common careless slip.
Compound shapes: the top mark-loser
Compound (or composite) shapes are the single biggest source of dropped marks in 11+ geometry, because children rush and add the wrong lengths. The method is always the same: split the shape into rectangles, or subtract a hole.
- Divide the L-shape into two rectangles with a light pencil line.
- Find the missing side lengths by subtracting the known lengths (opposite sides of the whole shape must match).
- Calculate each rectangle's area, then add them together.
Worked example: an L-shape is 10 cm wide and 8 cm tall overall, with a 4 cm by 5 cm rectangle removed from the top-right corner. Whole rectangle area = 10 × 8 = 80 cm². Removed piece = 4 × 5 = 20 cm². Compound area = 80 − 20 = 60 cm². For a shaded-region question, the logic is identical: outer area minus inner area.
Coordinates and transformations
Year 6 papers extend to all four quadrants, so pupils must read coordinates including negative values, always x before y — “along the corridor, up the stairs.” Common tasks include plotting the fourth corner of a rectangle, reflecting a point across the x- or y-axis, and translating a shape a given number of squares. Under a reflection in the y-axis, the point (3, 2) becomes (−3, 2); under a translation of 4 right and 2 down, it becomes (7, 0). Sketch lightly on the diagram rather than trying to picture it.
Exam traps to rehearse
- Answering perimeter when the question asked for area, or vice versa — underline the last line of every question.
- Measuring a not-to-scale diagram instead of calculating from the given angle facts.
- Forgetting units, or mixing cm and mm within one question without converting.
- Missing a hidden side length in a compound shape because opposite sides were not matched.
- Miscounting a cube net — test by mentally folding it.
Build fluency with our free geometry worksheets, then pressure-test it against a timed mock paper or a centre-specific mock for your target school. The revision hub maps every maths topic so you can track coverage.
Frequently asked questions
Is a calculator allowed in the 11+ geometry section?
No. GL, CSSE and ISEB papers are all non-calculator, so children must be confident with mental and written arithmetic when working out angles, areas and perimeters.
Are the diagrams drawn accurately?
Usually not. 11+ diagrams are often deliberately not to scale, so pupils should always calculate using the labelled measurements and angle rules rather than measuring with a ruler or protractor.
When should my child start geometry practice?
Core angle and area work suits Year 5, with coordinates, transformations and compound shapes firming up in Year 6. Starting angle facts and area formulas early gives plenty of time to reach exam-level compound-shape questions.