Polygons for kids
A polygon is a closed, flat shape with straight sides. Its name tells you how many sides it has. Quiz for kids, parent help below.
🧒 Kids: how many sides?
Count the straight sides. A polygon has the same number of corners as sides!
▶ Quiz 🔷 More practice 📐 Area and perimeter
💡 Trick: Is it closed? Are all the sides straight? Then it is a polygon!
More on shapes and lines: Lines, rays and segments · Polygons · Types of triangles · Quadrilaterals · Parts of a circle · Faces, edges and vertices
This part is for grown-ups: the key idea, pictures to draw, what to say, common mistakes, questions with answers and free printables.
The trick: closed, flat, straight
Ask three questions about any shape. Is it flat? Is it closed, with no gaps? Are all the sides straight? Three yeses make a polygon. A circle fails the last question, and an open shape fails the second.
- Triangle: closed, straight sides: a polygon
- Circle: curved: not a polygon
- A shape with a gap: open: not a polygon
- A cube: not flat: a 3D shape, not a polygon
Patterns to spot
- A polygon has the same number of sides as vertices.
- Each extra side adds one to the name: pentagon 5, hexagon 6.
- A regular polygon has as many lines of symmetry as sides.
- The more sides a regular polygon has, the more it looks like a circle.
- Any polygon can be cut into triangles from one corner.
- Squares and equilateral triangles are the regular polygons children meet first.
Key words
- Polygon: a closed, flat shape made only of straight sides.
- Side: one of the straight line segments that make the shape.
- Vertex: a corner where two sides meet. The plural is vertices.
- Regular polygon: all sides the same length and all angles the same size.
- Irregular polygon: sides or angles that are not all equal.
- Concave: a polygon with at least one corner that points inwards.
Why it matters: Polygons are the shapes behind almost all of geometry. Naming them by their sides leads straight to perimeter, area and angles.
See it: pictures to draw with your child
Draw these on paper, or build them with straws, paper and boxes. Holding and turning real shapes makes the words stick.
What your child already knows
Your child already knows triangles, squares and rectangles. Polygon is just the family name for every closed shape with straight sides, so this topic connects shapes they already know.
In real life: Road signs are a great place to start: a stop sign is an octagon and a yield sign is a triangle. Tiles, honeycombs and football patches are hexagons and pentagons.
Polygon names from 3 to 10 sides
| Sides | Name | Where you see one |
|---|---|---|
| 3 | Triangle | A slice of pizza, a yield sign |
| 4 | Quadrilateral | A door, a book, a kite |
| 5 | Pentagon | The outline of a simple house drawing |
| 6 | Hexagon | A honeycomb cell, a nut for a bolt |
| 7 | Heptagon | Some coins, like the UK 50p |
| 8 | Octagon | A stop sign |
| 9 | Nonagon | Rare: a star-shaped tile outline |
| 10 | Decagon | Some clocks and coins |
The start of each name counts the sides: tri means 3, penta 5, hexa 6, octa 8 and deca 10. An octopus has 8 arms, and an octagon has 8 sides.
Worked examples
Example 1: Is it a polygon?
- A shape has 5 straight sides and no gaps.
- It is closed and the sides are straight, so it is a polygon: a pentagon.
Example 2: Count the vertices
- A hexagon has 6 sides.
- Sides and vertices always match, so it has 6 vertices.
Example 3: Regular or irregular?
- A shape has 4 sides of 5 cm, 5 cm, 5 cm and 3 cm.
- The sides are not all equal, so it is an irregular quadrilateral.
Common mistakes
What to say to your child
A short script for your first session. Pause after each line and let your child answer.
- “Is the shape closed?”
- “Are all the sides straight?”
- “Then it is a polygon. Let’s count the sides.”
- “How many corners does it have?” (The same number.)
- “What is a 6-sided polygon called?” (A hexagon.)
- “Are all the sides the same length?” (Then it is regular.)
Questions to try (answers below)
Ask these out loud, with pictures or real objects to hand. The last one is a stretch.
- How many sides does a pentagon have?
- What is a polygon with 8 sides called?
- Is a circle a polygon?
- How many vertices does a hexagon have?
- A shape has 3 equal sides and 3 equal angles. What is it?
- Is a square a regular polygon?
- Is a rectangle that is not a square regular?
- What does “deca” mean?
- Stretch: how many triangles can you cut a pentagon into from one corner?
Show the answers
- 5
- an octagon
- No, it has a curved side
- 6
- a regular triangle (equilateral)
- Yes
- No, its sides are not all equal
- 10
- 3
Games to play at home
Shape hunt
Find polygons around the house and name each one by counting its sides.
Straw shapes
Make polygons from straws or sticks and clay. Who can make a hexagon? An octagon?
Polygon or not?
Draw shapes for each other, some with curved or open sides. The other says polygon or not, and why.
A 5-day plan for polygons
Ten minutes a day is enough. Short, regular practice works far better than one long session.
- Day 1: Learn it with the pictures above: draw them on paper or build them with real objects, and talk them through.
- Day 2: Read the script together, then ask the first four questions.
- Day 3: Do the quiz at the top of the page and read the working for anything missed.
- Day 4: Play one of the games at home for ten minutes.
- Day 5: Ask the rest of the questions, then do a round of the matching practice skill.
By grade
Grade 2 (Common Core 2.G.A.1) names triangles, quadrilaterals, pentagons and hexagons by their sides and angles. Grade 3 (3.G.A.1) sorts quadrilaterals, and grade 5 (5.G.B.3, 5.G.B.4) sorts polygons into families.
CBSE families: Fun with Shapes (class 3), Shapes Around Us (class 4) and Shapes and Patterns (class 5) use the same names.
More for each grade: Grade 2 math and the CBSE class 2 maths guide; Grade 3 math and the CBSE class 3 maths guide; Grade 4 math and the CBSE class 4 maths guide; Grade 5 math and the CBSE class 5 maths guide.
What comes next
Next, look closely at two polygon families: types of triangles and quadrilaterals. Then find the perimeter by adding the sides.
Worksheets and more practice
Print a free worksheet with an answer key, or keep practicing online with geometry practice.
Naming 2D shapes
PerimeterMore printables: 2D shapes worksheet · quadrilaterals worksheet · make a fresh test
More: geometry for kids · shapes for kids · practice · 2D shapes chart · 3D shapes chart
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Questions parents ask
What is a polygon?
A closed, flat shape made only of straight sides, like a triangle, square or hexagon.
Is a circle a polygon?
No. A circle has a curved edge, and every side of a polygon must be straight.
What is a regular polygon?
A polygon whose sides are all the same length and whose angles are all the same size, like a square.
What is a polygon with 6 sides called?
A hexagon. A polygon with 5 sides is a pentagon, and one with 8 sides is an octagon.
What grade learns about polygons?
Grade 2 names them by their sides, and grades 3 to 5 sort them into families such as quadrilaterals.