Lesson Notes By Weeks and Term - Junior Secondary 2

Circle

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TERM – 1ST TERM

WEEK TEN

Class: Junior Secondary School 2

Age: 13 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC TECHNOLOGY

Topic:  CIRCLE

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

  1. Define circle
  2. Identify the types and Parts of a circle
  3. Construct Targets and Normal to a given Circe and two to two equal and unequal circles

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS:   Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher describes and explain what a circle is, to the students.

Students pay

attention

STEP 2

EXPLANATION

Teacher identify and discuss the types and parts of a circle.

Students pay

attention and

participate

STEP 3

DEMONSTRATION

Teacher guide students to construct circles.

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

 

NOTE

CIRCLE

A circle is a two-dimensional geometric shape that is perfectly round. It is defined as the set of all points in a plane that are equidistant from a fixed center point. The distance from the center to any point on the circle is called the radius. The ratio of the circumference (the distance around the circle) to the diameter is constant and denoted by the mathematical constant π (pi).

Parts of a a circle

A circle has several key parts:

 

  1. Center: The central point/vertex from which all points on the circumference are equidistant.
  2. Radius: The distance from the center to any point on the circumference. All radii in a circle are of equal length.
  3. Circumference: The total distance around the circle.
  4. Diameter: The longest chord (a line segment connecting two points on the circle) that passes through the center. It is equal to twice the radius.
  5. Chord: A line segment connecting two points on the circle.
  6. Segment: A segment is the region between a chord and the arc enclosed by the chord. Segments can be classified as minor segments (smaller part) and major segments (larger part) based on the size of the corresponding arcs.
  7. Arc: A portion of the circumference of a circle.

Bisection, construction of tangent and normal to given circle

How to construct a Centre of Circle using just a compass and a straightedge

Procedure

  1. Draw a line across the circle to make a “chord”
  2. Construct the perpendicular bisector of that chord to make a diameter of the circle
  3. Construct the perpendicular bisector of that diameter to get the centre of the circle

Construct an internal tangent to two unequal circles

Procedure

  1. Draw two vertical centre lines at A and B 100 apart;
  2. Draw one horizontal centre line;
  3. Draw two unequal circles Ø30 and Ø58 at A and B respectively;
  4. Draw another circle Ø88 (Ø58 + Ø30) at centre B;
  5. Bisect AB and draw semi-circle on AB to intercept circle Ø88 at D;
  6. Join BD to locate point T on circle Ø58;
  7. Draw a line parallel to BD from A to locate point P on circle Ø30;
  8. Join PT to obtain the internal tangent;

EVALUATION: 1. What is a circle?

  1. Identify and describe the parts of a circle.
  2. Using only a compass and a ruler, construct a tangent to two unequal circles.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively