How to explain sort two-dimensional shapes in 2D shapes to your student: Example question
31 October 2026
Sorting two-dimensional shapes helps children recognise important properties like corners and side lengths. Using a Carroll diagram makes it easier to group shapes by these features.
Example question
Sort this isosceles triangle using a Carroll diagram. The diagram sorts shapes by two properties: number of corners (4 or less) and sides (all the same length or different lengths).
Step 1: Look at the triangle. It has 3 corners.
Step 2: 3 is 4 or less, so it goes in the '4 or less corners' column.
Step 3: The triangle's sides are not all the same length. It goes in the 'sides of different lengths' row.
Step 4: Place the triangle in the box where '4 or less corners' and 'sides of different lengths' meet.
The triangle is sorted into that box.
| All sides same length | Sides different lengths | |
|---|---|---|
| 4 or less corners | Isosceles triangle | |
| More than 4 corners |
Key insight: After this example, your child will be able to spot how many corners a shape has and whether its sides are all the same length. They can now practise sorting other 2D shapes in the same way.
