Lesson plan Grade: Subject: Mathematics Topic: Duration: Date: Subtopic: sum of interior of and Simple polygons

General objectives Upon completion of this lesson students should: 1. Demonstrate understanding of summation of angles in a 2. Perform Calculations to find the sum of angles in a simple polygon

Specific objectives Upon completion of this lesson students should be able to:

1.1 Perform activities to prove the sum of interior angles of a pentagon 1.2 Conduct activities to prove the sum of interior angles of simple polygons 1.3 Calculate correctly the sum of the interior angles of interior angles of any given polygon

Content 1.1.1 Activities to prove the sum of interior angles of a pentagon 1.1.2 Activities to prove the sum of interior angles of simple polygons 1.1.3 Calculation of the sum of interior angles of simple polygons (n – 2)180 Materials Papers with polygons draw on them Activity chart showing the relationship between interior angles of a polygon Crayons Marker Instruction sheet for cooperative leaning groups

Skills to be developed Reasoning Analytical Application

Strategies/Techniques/methods Guided discovery approach Cooperative learning groups Demonstration of calculations Drill and practice of calculations Explanation of key concepts Questioning to gain feed back Oral Discussion

Previous knowledge

Students already know the sum of interior angles of a and of , students already knows the concept of angles.

Introduction

Teacher will introduce the lesson with a recapitulation of the previous lesson, taking the form of an oral discussion Re: Interior angles in a and in a triangle. The teacher and students will discuss the procedures for the experiment as well as the result of the experiments that were perform to find the interior angles of those polygons.

Procedures

Step 1 teacher will introduce the lesson. Teacher will ask students for suggestions as to how we will find out the sum of interior angles of any given polygon. Students might say that we could measure all the angles in the polygons and that we could do a similar triangle experiment as with the quadrilateral to see the number of in each polygon. Step 2 Teacher will issue the materials of polygons, crayons and instruction sheets to the each of the six co-operative learning groups that will be instructed to from. Students will be guided to draw as many as is possible triangles in each polygon that will not overlap. Students will use different crayons to colour each triangle. Step 3 A representative of each group will give a presentation of their findings and fill in the respective slots on the activity chart with a marker. Students will fill in the sides of the polygons, the number of triangles and hence from the pattern deduce the sum of the interior angles of the polygon. Step 4 teacher will explain the findings and give students the formula (n -2)180 where n is the number of sides. Students will be asked to perform calculations using (n -2)180 to find the sum of interior angles of any given polygon.

Summary Teacher will recapitulate the lesson with an oral discussion Re: interior angles of and other simple polygons

Assessment: written activity

1 Using the formula (n- 2)x 180n , Find the interior angles of the following polygons

- An - A - A polygon with fourteen sides - A polygon with twenty sides

3. Find the value of x in each of the following