Lesson+6+-+Areas+of+Regular+Polygons

= Lesson #6 =

Title of lesson: Areas of Regular Polygons
Description of lesson: Students will use what they've learned so far about finding the areas of triangles to find the areas of regular polygons. Regular polygons can be split into multiple Isosceles triangles, so the students will use what they've learned so far not only to find the area of a regular polygon, but to understand the area formula that we typically use to find the area of a regular polygon.

Assignment: We will work as a large group, in small groups and individually to solve for the areas of various triangles. We'll begin the lesson with a warm-up problem where students will work individually to find the area of a kite using what they learned in the previous lesson. After the students have been given 5 minutes to work individually, we will take 5 minutes to discuss the solution as a class.

A video slide show will be shown at the beginning of the lesson to review what a regular polygon is as opposed to an irregular polygon. Following the video, a regular polygon will be displayed on the smartboard/promethean board and we will discuss how the polygon can be split into multiple congruent Isosceles triangles, each with a side of the polygon as a base. We will use the properties of a regular polygon to show how the triangles are all congruent. This will take approximately 10 minutes. Once we've split the polygon into multiple triangles, we will work together to solve for the area of each triangle and combine them to find the area of the polygon. This will take approximately 5 minutes. Another regular polygon will then be displayed on the board and the students will be divided into groups of 3-4 and asked to divide the polygon into multiple triangles, find the area of each triangle, and combine them to find the area of the polygon. They will be given 10 minutes to work on this. After the students have had time to work in their groups, we will spend about 5 minutes discussing the solution as a class. A third regular polygon will then be displayed on the board and the students will be shown the formula for finding the area of a regular polygon (A = half the apothem (distance from the center of the polygon to the center of any side) times the perimeter) and how it relates to the way we found the area of a regular polygon by splitting it into multiple congruent triangles. We will then solve for the area of the polygon using the area formula.

For homework, the students will be assigned a short worksheet of practice problems and asked to blog about the lesson: what they understood, what they didn't understand, what they thought could have been done differently, etc.

Resources/materials needed: Students may use the textbook as an additional reference. We will be using the smartboard/promethean board during class and students will need to bring their notebooks, and a pencil. The worksheet will be posted on the class website along with the video slide show to be used for the lesson:

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Technology reflection: The slide show for the lesson will reinforce learning and work as a review before we get started with the lesson. The video will provide the properties and definitions used in class so that students can use them for their homework. They will also provide parents with a source for information if they'd like to check or help with the students' homework.

Evaluation: I will need to focus on making sure all of the students' needs are met by the lesson and that no one is being left behind. I will need to make sure I keep on track in terms of timing so that we are able to cover the unit in the time allotted. I will also need to make sure I have a backup plan in place just in case there is a technical problem with any of the technology. For example, I'll need to make sure I have chalk or dry erase markers in case the smartboard/promethean board isn't working. I'll also need to make sure I have a few copies of the homework printed in case there are any problems with the class website or there are students who can't access the internet for some reason.

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