You learned what makes a shape a shape (What Makes a Shape a Shape): sides and corners matter, but color, size and turning don’t. Now you can name shapes by counting.
| Name | Sides | Corners (angles) |
|---|---|---|
| triangle | 3 | 3 |
| quadrilateral | 4 | 4 |
| pentagon | 5 | 5 |
| hexagon | 6 | 6 |
Why it works
A corner is where two sides meet, so a closed flat shape always has as many corners as sides. The names count, too: tri- means 3, quad- means 4, penta- means 5 and hexa- means 6.
Worked example: Name it
A flat shape has 5 straight sides. What is it?
- Penta- means 5.
- A shape with 5 sides and 5 corners is a pentagon.
Answer: a pentagon
Worked example: A cube
How many faces does a cube have?
- Each face is a square.
- Top, bottom, front, back, left, right: 6 faces.
- A cube also has 8 corners (vertices) and 12 edges.
Answer: 6 faces
Key idea
Name flat shapes by counting sides or corners: 3 triangle, 4 quadrilateral, 5 pentagon, 6 hexagon. A cube has 6 square faces.
Common mistake
Thinking a shape is only a hexagon if it looks like a honeycomb cell. Any closed flat shape with 6 straight sides is a hexagon, even an L-shape like B. Check: count the sides with your finger.
Grown-up tip: Go on a shape hunt: find triangles, quadrilaterals and hexagons around the house, and count their sides.