Identifying and Classifying Polygons

Since much of the vocabulary for polygons will be new to your students, it is a good idea to begin by spending a day making connections between objects in your classroom and the new vocabulary. This will allow you to tie what the students are learning to real-life examples of polygons.

Materials: Colored poster paper, straight edge, and scissors.

Preparation: Cut out the following polygons and post them. Make sure that they are large enough for the entire class to see. Use different colors for each polygon and write the name of each in the center of the cut-out.

Prerequisite Skills and Concepts: Students should know about triangles and rectangles and basic properties of these shapes such as the number of sides of each.

• Ask: (While pointing at the triangle)
What shape is this? (triangle) Can anyone tell me what makes a triangle different from other shapes?
Students should identify that a triangle has three sides. Some may also say that it has three angles. Write these properties below the shape on the board.
• Ask: (Write the word tricycle on the board) How many of you had a tricycle when you were little boys and girls?
How many wheels does a tricycle have?
What do a tricycle and a triangle have in common?
When students identify that a tricycle has three wheels and a triangle has three sides, make the connection between the prefix tri- and the number three.
• Below the properties of the triangle, write "Tri means 3."
• Ask: (While pointing at the quadrilateral) This shape is called a quadrilateral. What can you tell me about it?
Students should identify that a quadrilateral has four sides. Some may also say that it has four angles. Write these properties below the shape on the board.
• Continue by explaining that quad- means four. Then write "quad means 4" below the quadrilateral.
• Ask: (While pointing at the pentagon)
This is a pentagon. What can you tell me about it?
Again, students should identify the number of sides and possibly angles for a pentagon.
• Ask: Who knows what prefix means five in the word pentagon?
Some students may also beat you to the punch line by informing you that pent- means five before you ask this question.
• Continue for the hexagon and octagon. Some students will be thinking ahead and already have the prefixes for 6 and 8.

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