Lesson Plan 1.docx

LESSON PLAN

A. Identity School

: Mor Din Daeng Demonstration School

Subject

: Mathematics

Sub Subject

: Incribed angle and Center angle

Class

: M.3/1

Standar Competence

: Determine the element of circle, inscribed angles, and center angles

Basic Competence

: Know about inscribed and central angles and Applying the relation of central angle and inscribed in circle

Indicators

: 1. Redrawing central and inscribel angle 2. Identify central and inscribed angle 3. Differentiate central and inscribed angle 4. Define relation between central and incribed angle

B. Learning Objectives 1. Students can draw central and inscribed angles 2. Students identify central and inscribed angles 3. Students differentiate central and inscribed angles 4. Students define relation between central and inscribe angels C. Learning Material 1. Part of circle a. Radius b. Diameter c. Center Point d. Tali busur 2. Inscribed and central angles application in daily life : a Clock, a Disk, a Fan, etc 3. Inscribed and Central angles In the figure below,

APB is drawn in circle O by determining AB and then placing

poin P somewhere on the circumference beside AB.

Explanation : O

: Center Point

OA = OB

: Radius

P

: Point in Circumference Circle

PA = PB

: Chord

APB

: Inscribed Angle

AOC

: Central Angle

AB

: Arc

Incribed Angles is an angle whose point lies on a circle and whose sides are chords of the circle

Central Angles is point is at the center of a circle.

4. Relationship between the size of Inscribed Angle and Center Angle that intercept the same arc The size of Center angle = 2 * the size of inscribed angle D. Source/Material and Tool Source/Material

: Math 3 For Junior High School (Japan Book)

Tool

: Circle Picture, Student worksheet

Media

: Geogebra Application (Indonesia), Discovery Disk

E. Learning Methode Metde

: Open Approach

Mthode

: Dialogue, Discussion, assignment

F. Learning Activity A. Learning Activity Teacher

Students

Timer

Introduction

5 minutes

a) Apperception:

2 minutes

Teacher remind students about Student give respon by mention part of circle that they have some part of circle such as arc, known.

Ex

:

arc,

radius, radius, diameter, etc

diameter, etc b) Motivation:

2 minutes

Gives motivation about the Pay attention with the teacher’s importance of inscribed angle explanation. They can mention and central angle in daily life.

some thing such as clock, Disk, fan.

c) Goal:

1 minutes

Informing students about the Pay attention with the teacher’s learning objectives

explanation

Main Activity

35 minutes

a) Exploration:

25 minutes

1. Guid students to draw the 1. Try to draw the center and inscribed and center angle.

inscribed angle by themself.

2. Guid the student to define 2. The student try to define the the inscribed and center

inscribed and center angle by

angle.

themself.

3. Guid the student to know 3. Students try to use discovery better

the

inscribed

the

inscribed and center angle.

disk (tool) for they know better about the inscribed and center

angle. 4. Give

students

contextual

some 4.

problems

in

Students

do

worksheet

individually.

worksheet 5. Guiding students which is do 5. Students ask the teacher if they not understand the problem

don’t know about step to do the

in worksheet.

exercise

6. Guide students to discuss 6. Share idea/opinion/answer about the problem 7. Choose a student to present 7. Present their work in front of their work in front of class

class

8. Giving chance for student to 8. The student ask what they do ask about the problem in the

not understand in that problem

worksheet b) Elaboration:

5 minutes

1. Make the condition of class to 1. Back to the normal class be normal 2. Guides

students

with

the 2. Answer the question by mention:

is

the

the relationship between the size

relationship between the size

of inscribed and central angle that

of inscribed and central angle

intercept the same arc

question:What

that intercept the same arc c) Confirmation:

5 minutes

1. Ask the students to find out 1. Explain what they still do not what they do not understand

understand

2. Do dialogue to make clear 2. Continuing the dialogue until students’ understanding and

understand about the material

give feed-back 10 minutes

Closing 1. Guides

students

reflection

to

make 1. Help the student to remind what are inscribed and center angle, what is the relationship between the size of incribed angle and center angle that intercept the

2. Close the lesson

same arc 2. Students

together

close

the

lesson.

G. Evaluation Individual test (essay)

Activator - Central and Inscribed Angles Directions: Measure each central and inscribed angle for each circle. Record your measurements in the chart. B

C

A 1.

2.

O

O

A

C

B

B

3. A

O

D

C

Ci rcle 1

Circle 2

Circle 3

AC

AC

ADC

Circle

Central Angle Inscribed Angle

From exercise above that you’ve done, what is the relationship between the size of inscribed angle and central angle ?