Class: Junior Secondary School 3 (JSS3, JSS 3)
Term: 2nd Term
Week: 9
Age: 14 years
Duration: 45 minutes
Subject: Mathematics
Curriculum Theme: Mathematics
Previous Lesson: Volume and Surface Areas of Cylinders and Cones
Topic: Construction (Part 1)
Subject Matter: Bisecting of line segments, Bisecting of angles, Constructing simple shapes

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:
(a) Explain the meaning of construction in geometry.
(b) Describe and outline the steps for bisecting lines and angles.
Affective Domain:
(a) Appreciate the importance of accuracy and neatness in geometric constructions.
Psychomotor Domain:
(a) Bisect a line segment and an angle using a compass and ruler.
(b) Construct simple geometric shapes accurately.
Social Domain:
(a) Work cooperatively in pairs while performing construction tasks.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum
Lagos State Unified Scheme of Work for Junior Secondary Schools
Math is Fun – Geometric Constructions
Relevant Textbooks

Instructional Materials

The teacher will teach this lesson with the aid of:

Ruler
Compass
Protractor
Whiteboard and markers
Chart showing geometric construction steps
Sample constructed shapes

Rationale for the Lesson

Construction skills help pupils develop accuracy, precision, logical thinking, and practical problem-solving abilities essential in geometry and technical drawing.

Prerequisite/Previous Knowledge

Pupils already know basic geometric terms and have used rulers and compasses to draw lines, angles, and simple shapes.

Lesson Content/Board Summary

Lesson Content

Construction – Bisecting Lines, Angles, and Shapes for JSS 3

Bisecting a Line Segment

A line segment is a straight path between two endpoints. To bisect means to divide it into two equal parts using a compass and ruler.
The following are the steps for bisecting a line segment:

Draw the line segment AB.
Place the compass on point A and draw an arc above and below the line.
Without changing the compass width, place it on point B and draw another pair of arcs cutting the first arcs.
Join the points of intersection to divide AB into two equal parts.

Bisecting an Angle

An angle is formed when two lines meet at a point called the vertex. To bisect an angle means to divide it into two equal angles.
The following are the steps for bisecting an angle:

Draw angle ∠ABC.
Place the compass on the vertex B and draw an arc cutting the two arms of the angle.
From each cut point, draw two arcs that intersect within the angle.
Draw a straight line from B through the intersection of the arcs to bisect the angle.

Constructing Simple Shapes

Simple shapes like triangles and quadrilaterals can be constructed using given lengths and angles.
Examples include:

Constructing an equilateral triangle using equal sides.
Constructing a square using right angles and equal sides.
Constructing an isosceles triangle with two equal sides.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Explanation, Visual Aids, Group Work

Instructional Procedures

To deliver this lesson, the teacher will adopt the following steps:

Step 1: Introduction (Set Induction)

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher shows a chart with different geometric constructions and asks pupils what tools are used to create them.
Pupils’ Activity: Pupils observe and respond based on prior knowledge.
Learning Point: Pupils recall previous experience with geometry tools.

Step 2: Meaning of Construction

Time: 7 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains the meaning of construction and outlines tools used.
Pupils’ Activity: Pupils listen and ask questions.
Learning Point: Pupils understand the meaning and purpose of construction.

Step 3: Bisecting Line Segments

Time: 10 minutes
Teaching Skill: Demonstration
Teacher’s Activity: The teacher demonstrates how to bisect a line segment as shown in the board summary.
Pupils’ Activity: Pupils practice bisecting a line segment.
Learning Point: Pupils learn accurate construction steps.

Step 4: Bisecting Angles and Constructing Shapes

Time: 10 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher demonstrates angle bisection and constructing simple shapes.
Pupils’ Activity: Pupils attempt constructions in their notebooks.
Learning Point: Pupils apply construction principles.

Step 5: Note-Taking

Time: 5 minutes
Teaching Skill: Reinforcement
Teacher’s Activity: The teacher guides pupils to copy the board summary.
Pupils’ Activity: Pupils write notes.
Learning Point: Pupils retain key points.

Step 6: Evaluation/Review

Time: 5 minutes
Teaching Skill: Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

What does it mean to bisect a line segment?
State the steps for bisecting an angle.
Construct an equilateral triangle using a side of 5 cm.
Pupils’ Activity: Pupils answer and perform tasks.
Learning Point: Pupils demonstrate understanding.

Step 7: Conclusion

Time: 3 minutes
Teaching Skill: Summary
Teacher’s Activity: The teacher summarizes the lesson and reinforces accuracy in construction.
Pupils’ Activity: Pupils listen.
Learning Point: Pupils recall major points.

Lesson Keywords

Construction – Drawing shapes using tools
Bisect – Divide into two equal parts
Angle – Space between two intersecting lines
Arc – Part of a circle drawn with a compass
Segment – Part of a line between two points

Differentiation

Provide additional support for slower learners through guided hand-over-hand practice; challenge fast learners with extra construction tasks.

Note for teachers using this lesson plan

Ensure pupils maintain accuracy and neatness; always check compass width before drawing arcs.