Sides and vertices
Count edges and corners accurately in 2D shapes.
Quick answer
You can count the straight lines (sides) and the points where lines meet (vertices) in 2D shapes by carefully looking at each edge and corner. A side is a straight line, and a vertex is where two sides meet at a point.
Learning outcome
By the end of this page, you will be able to count the number of sides and vertices in any 2D shape.
- You can name the sides and vertices of common shapes like triangles, squares, rectangles, pentagons, and hexagons.
- You can explain the difference between a side and a vertex.
- You can draw and identify 2D shapes with a given number of sides and vertices.
- You can find real-life examples of shapes around you and count their sides and vertices.
Why this matters
Knowing about sides and vertices helps you understand shapes better. It's useful in art, building, puzzles, and even in games like football where you might count the sides of a field or the corners of a goal. When you grow up, you'll use this knowledge for drawing, designing, and understanding the world around you.
How it works
Let's think of a shape like a triangle. A triangle is a 2D shape with three straight lines (sides) and three points where the lines meet (vertices).
- Count the sides: Look at the shape and count how many straight lines it has.
- Count the vertices: Look at the shape and count how many points where lines meet.
- Match them up: The number of sides and vertices often match for regular shapes.
For example, a square has four sides and four vertices. A pentagon has five sides and five vertices. A hexagon has six sides and six vertices.
Examples you can see
Let’s look at some shapes and count their sides and vertices:
| Shape | Sides | Vertices |
|---|---|---|
| Triangle | 3 | 3 |
| Square | 4 | 4 |
| Rectangle | 4 | 4 |
| Pentagon | 5 | 5 |
| Hexagon | 6 | 6 |
You can imagine drawing these shapes and counting each side and vertex carefully. For example, a triangle has 3 sides and 3 vertices. A rectangle has 4 sides and 4 vertices.
Try it as a mini adventure
Adventure: Shape Hunt in Your Home
You are going on a shape hunt around your house. You must find 5 different shapes and count how many sides and vertices each one has. You can look for:
- A triangle (like a slice of pizza)
- A square (like a picture frame)
- A rectangle (like a book cover)
- A pentagon (like a star)
- A hexagon (like a honeycomb or a nut)
For each shape, write down how many sides and vertices you found. For example:
- Pizza slice (triangle): 3 sides, 3 vertices
- Picture frame (square): 4 sides, 4 vertices
- Book cover (rectangle): 4 sides, 4 vertices
- Star (pentagon): 5 sides, 5 vertices
- Honeycomb (hexagon): 6 sides, 6 vertices
Now, try to draw each shape and label its sides and vertices. You can even make a shape collage with different shapes and their sides and vertices!
Common mistakes
- Mistake: Counting a side twice or missing one.
Why it happens: When you're counting, you might accidentally look at the same side twice or not look carefully.
Fix: Use a finger or a pen to trace each side once as you count. - Mistake: Thinking a vertex is a side or vice versa.
Why it happens: The words "side" and "vertex" sound similar, and they're both parts of a shape.
Fix: Remember that a side is a straight line, and a vertex is a point where lines meet. - Mistake: Confusing a circle with a shape that has sides and vertices.
Why it happens: A circle is a curved shape, not made of straight lines.
Fix: A circle has no sides or vertices because it's a smooth curve.
Parent and carer guide
Help your child understand sides and vertices by:
- Using everyday objects like books, plates, and toys to point out shapes.
- Playing the shape hunt game together and counting sides and vertices.
- Using drawing or cutting out shapes to make it more visual.
- Encouraging your child to say the shape name and the number of sides and vertices.
- Noticing when your child makes a mistake and gently helping them correct it.
Remember, it’s okay if they don’t get it right the first time. Practice makes progress!
Practice questions
- How many sides and vertices does a square have?
Answer: 4 sides, 4 vertices - How many sides and vertices does a pentagon have?
Answer: 5 sides, 5 vertices - How many sides and vertices does a hexagon have?
Answer: 6 sides, 6 vertices - How many sides and vertices does a triangle have?
Answer: 3 sides, 3 vertices - How many sides and vertices does a rectangle have?
Answer: 4 sides, 4 vertices - How many sides and vertices does a circle have?
Answer: 0 sides, 0 vertices - How many sides and vertices does a heptagon have?
Answer: 7 sides, 7 vertices - How many sides and vertices does an octagon have?
Answer: 8 sides, 8 vertices - How many sides and vertices does a decagon have?
Answer: 10 sides, 10 vertices - How many sides and vertices does a dodecagon have?
Answer: 12 sides, 12 vertices
FAQ
What is a side in a shape?
A side is a straight line that makes up a shape. For example, a triangle has three sides.
What is a vertex in a shape?
A vertex is a point where two sides meet. For example, a triangle has three vertices.
Can a shape have more sides than vertices?
No, for regular shapes, the number of sides and vertices is always the same.
Do all shapes have the same number of sides and vertices?
Yes, for regular 2D shapes, the number of sides and vertices match. A circle is an exception because it has no sides or vertices.
How can I help my child learn sides and vertices?
You can use everyday objects, play shape games, draw shapes, and count sides and vertices together.