Naming Polygons

Recognize any of these shapes?

By: Keith Winberry

Using this tutorial

Icon Uses

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This button will take you to important videos.

What are Polygons?

According to wikipedia, in geometry a polygon is traditionally a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed chain. If you would like more information on the definition of a polygon click on the “i” link to the right.

Types of Polygons

There are many different types of polygons. Today we will learn the names of different polygons. Each time a shape gains an extra side the polygon gets a new name. To the right is a chart that names the polygons. Once there are more than 12 sides you can see that the shape usually takes that number and adds gon to the end of it. For example a 25 sided shape would typically be call a 25-gon. Once you have reviewed this click on the house icon at the bottom of the screen and try to name the shapes on the home page.

Number of sides

Name of polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon

8 Octagon

9 Nonagon

10 Decagon

11 Hendecagon

12 Dodecagon

13 13-gon

14 14-gon

How many sides?

To determine what type of polygon it is you should either count the number of lines or count the number of vertices. The vertices are indicated by the green arrows and the lines are indicated by the red arrows. Once you have found the number of sides or vertices you can refer to slide 4 to name the polygon.

Note: This shape has 6 vertices and lines so it is a hexagon.

Check for Understanding

1. A polygon with 10 sides is called a A)Decagon B)Triangle C) Quadrilateral D) Heptagon

2. A polygon with 4 sides is called a A) Hexagon B) Heptagon C) Dodecagon D)Quadrilateral

3. This shape is a

A) Heptagon B)Decagon C) Hexagon D) 14-gon

4. A polygon with 6 sides is called a A) Hexagon B) Decagon C) Quadrilateral D) Heptagon

5. This shape is called a A) Dodecagon B)15-gon C) Pentagon D)

Heptagon

If you want to check your answers click on the green box.

How did you do?

If you missed a few questions go back to slide 4 and find the correct answer. You may take the quiz as often as you wish. The goal is that you understand the material.

The purple button to the right is a video that will reinforce our goal of understanding polygons. This video will describe different polygons. Often people just need to hear something with a visual to understand. The video may seem elementary, but it is accurate.

Note-The video says a shape with 4 sides is a trapezoid, which is true, but for this lesson we will call it a quadrilateral

How big can a polygon get?

There is no limit to how big a polygon can be. In slide 4 we went to a 14-gon. I described in that slide that a polygon bigger than 12 is named by that number followed by-gon. I even used an example of a 25-gon. Lets look at some examples of really big polygons.

15-gon

20-gon

Compare and Contrast

Tell me in just a few sentences the differences in the two shapes to the right. In your explanation also tell me the names of the shapes to the right. Once you have completed this assignment you may click on the green button to compare your answer with the correct answer. Remember, you may go to previous slides. The goal is not to confuse you but rather to get you to understand the lesson.

Polygons in Real Life

I am sure at this point you are wondering, where am I ever going to use this in real life. Well, the answer to this one is simple. Just look around the room. Do you see any quadrilaterals? What about other shapes? You will come across these shapes numerous times even in your day to day life. To the right I will provide some examples.

HexagonPentagon

Octagon

Get Ready

Now I want you to get ready for another quiz. This time the shapes will look a little more odd. Remember to count the number of lines. Do not worry about how the shape looks. Often students let this mix them up. Use this time to go back to previous slides and prepare yourself for the quiz on the next slide. I am attaching a music video to the right that may be helpful. I hope you enjoy this. I think you will.

Check for Understanding 2

I want you to find the following: quadrilateral, hexagon, triangle, and pentagon

Once you think you have your answer check it with the correct answer by clicking on the green box.

Review

Remember that a polygon is named by the number of sides or vertices on the shape. You should also remember that a polygon with more than 12 sides is often called that number plus gon. It is important that you have a basic understanding of polygons because they are everywhere in your everyday life. You should also remember that polygons are a closed shape. If you want an extra website that will help review that material click on the yellow box to the right.

Rubric

Math - Using Polygons

         

Teacher Name: Mr. Winberry

Student Name:     ________________________________________

CATEGORY 4 3 2 1Completion All problems are 

completed.All but one of the problems are completed.

All but two of the problems are completed.

Several of the problems are not completed.

Explanation Explanation is detailed and clear.

Explanation is clear. Explanation is a little difficult to understand, but includes critical components.

Explanation is difficult to understand and is missing several components OR was not included.

Mathematical Reasoning Uses complex and refined mathematical reasoning.

Uses effective mathematical reasoning

Some evidence of mathematical reasoning.

Little evidence of mathematical reasoning.

Neatness and Organization

The work is presented in a neat, clear, organized fashion that is easy to read.

The work is presented in a neat and organized fashion that is usually easy to read.

The work is presented in an organized fashion but may be hard to read at times.

The work appears sloppy and unorganized. It is hard to know what information goes together.

Date Created: Jul 12, 2013 08:49 am (CDT)

Conclusion

I really hope you enjoyed this lesson on polygons. You will use this throughout your life. This tutorial will be available to you throughout the year so if you feel like you need to review the material feel free to do so. I hope you took this tutorial seriously because the information you learned here will be used throughout this course for the remainder of the year. The tutorial was created to help you and hopefully you have taken advantage of that. If you have any questions about the material ask the instructor. If you have questions about the grading refer to slide 13.

Thanks