TERM – 1^ST TERM

WEEK SEVEN

Class: Junior Secondary School 2

Age: 13 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC TECHNOLOGY

Topic: ANGLES II

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

To construct and bisect angles 90⁰, 45⁰, 60⁰. 30⁰

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures, mathematical sets, drawing instruments.

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher highlight the steps to construct and bisect angles 90⁰, 45⁰ and 60⁰

Students pay

attention

STEP 2

EXPLANATION

Teacher guide the students to construct those angles as he construct them on the board.

Students pay

attention and

participate

STEP 3

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

NOTE

ANGLES II

Bisection and Construction of Angles –90, 45, 60, 30 etc

To construct the bisector of angle 90⁰

Construct an angle of 90⁰ using ruler and compasses and bisect it.

Procedure:

Draw a line segment AB.
With A as the centre and a small radius, draw an arc cutting AB at M.
With M as the centre and the same radius as above, draw an arc cutting the previously drawn arc at N.
With N as the centre and the same radius as above, draw an arc cutting the previously drawn arc at P.
Again, with N as the centre and a radius more than half of PN, draw an arc.
With P as the centre and the same radius as above, draw an arc cutting the previously drawn arc at Q.
Join AQ cutting the arc at O and produced it to C.
With O as the centre and a radius more than half of OM, draw an arc.
With M as the centre and the same radius as above, draw another arc cutting the previously drawn arc at

point R.

Join AR. Thus, AR bisects ∠BAC

How to construct a 45-degree angle

Procedure

1: Stretch your compasses until it is more then half the length of AB. Put the sharp end at A and mark an arc above and another arc below line segment AB.

2: Without changing the width of the compasses, put the sharp end at B and mark arcs above and below the line segment AB that will intersect with the arcs drawn in step 1.

3: Join the two points where the arcs intersect with a straight line. This line is the perpendicular bisector of AB. P is the midpoint of AB.

4: Bisect the 90-degree angle to form a 45-degree angle.

To construct angle 60

Procedure

With a pencil and a straight-edge draw a straight line
Use compasses centered on one end of the line, draw an arc.
From where the arc crosses the line, draw another arc.
Join the end point of the line to where the two arcs intersect.

EVALUATION: 1. Construct angle 30⁰

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively

Lesson Notes By Weeks and Term - Junior Secondary 2