# Recognizing Shapes

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Recognizing Shapes
CCSS.MATH.CONTENT.2.G.A.1

## Basics on the topicRecognizing Shapes

Recognizing geometric shapes like triangles, quadrilaterals, pentagons, and hexagons is an important skill in geometry. Here's how to recognize four different types of polygon shapes:

Triangle:

A triangle is a polygon with three sides and three angles. Look for three straight sides that connect to form three vertices (corners). The sum of the interior angles of a triangle is always 180 degrees.

A quadrilateral is a polygon with four sides and four angles. Identify four straight sides that connect to form four vertices, or corners. The sum of the interior angles of a quadrilateral is always 360 degrees.

Pentagon:

A pentagon is a polygon with five sides and five angles. Look for five straight sides that connect to form five vertices, or corners. The sum of the interior angles of a pentagon is always 540 degrees.

Hexagon:

A hexagon is a polygon with six sides and six angles. Identify six straight sides that connect to form six vertices, or corners. The sum of the interior angles of a hexagon is always 720 degrees.

When trying to recognize these shapes, pay attention to the number of sides and corners, or vertices. Practicing with visual examples and drawing these shapes can further reinforce your ability to recognize them.

### TranscriptRecognizing Shapes

Nia and Nico are playing “I Spy” in the park, except this isn't a regular park! This is Polygon Park, so the visitors, are a bit shapely. In order to know who Nico and Nia are describing, they will need to practice, "Recognizing Shapes." We recognize a two-dimensional, or flat, shape by the number of straight sides and angles it has. An angle is like the corner of a shape; it's the space where two lines meet. It's important to count the number of sides and angles on a shape to identify what type of shape it is. Certain shapes have qualities that must always be true. We use these qualities to determine its type. A triangle is a shape with three straight sides and three angles. A quadrilateral is a shape with four straight sides and four angles. You may have heard of different types of quadrilaterals, like squares and rectangles. A pentagon is a shape with five straight sides and five angles. They can come in different sizes. A hexagon is a shape with six straight sides and six angles. Just like pentagons, they can come in different sizes too. Now that Nico and Nia know how to recognize shapes, they are ready to play "I Spy"! "I spy with my little eye something that has five straight sides and five angles." First, Nico should find a shape and count its sides and angles. Does this shape have five straight sides and angles? One, two, three, four, five; it has five straight sides! One, two, three, four, five; it has five angles! "Nia, do you spy a pentagon?" "I do!" " Ok, it's my turn. I spy with my little eyes something that has six straight sides and six angles." Take a moment and try to picture which shape Nico described. "Do you spy a hexagon, Nico?" "I do!" Did you also say a hexagon? While Nia and Nico take turns guessing, let's remember! Today we learned about recognizing shapes. We identify a two-dimensional, or flat, shape by the number of straight sides and angles it has. It's important to count the number of straight sides and angles on a shape to identify its type. Here is a chart that describes the qualities of triangles, quadrilaterals, pentagons, and hexagons. "I spy, with my little eyes, something that has three angles and three sides." "Oh, that's easy, Nia. You spy a triangle!" "Nope." "Huh? What is it, then?" "It's YOU, Nico!" "How could that be me?!" "See! It's you!"

## Recognizing Shapes exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Recognizing Shapes.
• ### Can you label the shape?

Hints

The sides go all the way around the edge of a shape. They are straight lines.

The angles are where two straight sides meet.

Solution

Here we can see the rectangle labelled correctly.

• ### Can you name these shapes?

Hints

Count the number of sides and angles to help you recall the name of the shape.

Think about the names of the shapes. For example, a tricycle has three wheels so a triangle has three sides.

Squares and rectangles both have 4 sides but a square has 4 sides that are all the same length.

Solution

Here we can see the names of each of the shapes.

• ### How many sides and angles?

Hints

Count the number of sides. These are the straight lines around the edge of the shape.

Count the number of angles. These are where two straight lines meet.

Each shape has the same number of sides as angles.

Solution

Triangle

• 3 sides
• 3 angles
Hexagon

• 6 sides
• 6 angles
Square

• 4 sides
• 4 angles
Pentagon

• 5 sides
• 5 angles
• ### Can you find the shapes in the picture?

Hints

Quadrilaterals have 4 sides and include squares and rectangles.

Count the number of sides each shape has to help you remember its name.

Think about the names of the shapes e.g. a tricycle has three wheels so a triangles has three sides.

Solution

Here we can see the shapes highlighted correctly. There are:

• 3 triangles
• 3 pentagons
• 2 hexagons
• ### Which shape is Nico thinking of?

Hints

Count the number of sides on each of these shapes.

Count the number of angles on each of these shapes.

Here we can see this shape has 1, 2, 3 sides.

Which shape above also has 3 sides?

Solution

Nico is thinking of a triangle. A triangle has:

• 3 sides
• 3 angles
• ### How many of each shape can you see?

Hints

Count the sides of each shape carefully. Remember, pentagons have 5 sides and hexagons have 6 sides.

Quadrilaterals have 4 sides and include squares and rectangles.

There are 20 shapes altogether. Add up the totals you have for each shape to check you have the right amount.

Solution

Altogether there are:

Triangles 6