Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 8
Age: 15 years
Duration: 45 minutes
Subject: Technical Drawing
Curriculum Theme: Technical Drawing
Previous Lesson: Triangles: Types and Construction Methods.
Topic: CIRCLE AND TRIANGLES
Subject Matter: Definition of a circle, parts of a circle including radius, diameter, chord, tangent, sector and quadrant, concentric circles, eccentric circles, labelling and neat presentation.

Specific Objectives

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

Cognitive Domain:

Define a circle.
Identify and name the different parts of a circle.
Explain the difference between concentric and eccentric circles.

Affective Domain:

Appreciate the importance of neatness and accurate labelling in technical drawing.
Develop an interest in drawing basic geometric shapes.

Psychomotor Domain:

Draw a circle accurately using appropriate instruments.
Label the parts of a circle correctly.
Draw examples of concentric and eccentric circles.

Collaborate effectively with peers during practical drawing exercises.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Senior Secondary Schools.
State Unified Scheme of Work for Technical Drawing (SSS 1).
Anyanwu, A. O. (2018). Technical Drawing for Senior Secondary Schools 1-3. Learn Africa Plc.

Instructional Materials

The teacher will teach this lesson with the aid of:

Drawing instruments (compass, ruler, set squares, protractor).
Charts showing the parts of a circle.
Pencils (HB, 2H).
Drawing sheets/notebooks.

Rationale for the Lesson

Understanding circles and their parts is fundamental in technical drawing. This lesson helps pupils to accurately interpret and create technical drawings that incorporate circular features, which are common in engineering, architecture, and design fields. It lays a foundation for more complex drawing concepts.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of simple geometric shapes and how to use basic drawing instruments like rulers and pencils.

Lesson Content/Board Summary

CIRCLE AND TRIANGLES

Definition of a Circle

A circle is a plane figure bounded by a continuous curved line, every point of which is equidistant from a fixed point called the centre.

Parts of a Circle

The following are the important parts of a circle:

Centre: The fixed point from which all points on the circumference are equidistant.
Circumference: The continuous curved line forming the boundary of the circle. It is the perimeter of the circle.
Radius (r): A straight line segment from the centre to any point on the circumference.
Diameter (d): A straight line segment passing through the centre and connecting two points on the circumference. It is twice the radius (d = 2r).
Chord: A straight line segment connecting any two points on the circumference. The diameter is the longest chord.
Tangent: A straight line that touches the circumference of a circle at exactly one point, without crossing it.
Arc: A part of the circumference of a circle.
Sector: An area of a circle enclosed by two radii and the arc between them.
Quadrant: A sector that represents one-quarter of a circle, formed by two radii at right angles (90 degrees) to each other.

Concentric Circles

Concentric circles are two or more circles that share the same centre point but have different radii. They appear as rings around a common centre.

Eccentric Circles

Eccentric circles are two or more circles that do not share the same centre point. Their centres are located at different positions.

Importance of Labelling and Neat Presentation

The following are reasons why labelling and neat presentation are important in technical drawing:

Ensures clarity and avoids ambiguity in drawings.
Helps in easy identification of different parts or features.
Facilitates accurate interpretation by others.
Reflects professionalism and attention to detail.
Reduces errors during manufacturing or construction.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and asks them to identify common objects around them that are circular in shape (e.g., clock, wheel, plate). The teacher then introduces the topic “Circle and Triangles” focusing on circles for this lesson.
Pupils’ Activity: Pupils respond by mentioning circular objects and listen attentively to the introduction.
Learning Point: Pupils are reminded of familiar circular objects and are prepared for the lesson.

Step 2: Definition of a Circle

Time: 8 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines a circle clearly and uses a compass to demonstrate how a circle is drawn, emphasizing the fixed centre and constant radius. The definition is written on the board.
Pupils’ Activity: Pupils listen, write down the definition, and observe the demonstration.
Learning Point: Pupils understand the fundamental definition of a circle.

Step 3: Parts of a Circle

Time: 10 minutes
Teaching Skill: Illustration/Demonstration
Teacher’s Activity: The teacher displays a chart showing a circle with its parts clearly labelled (radius, diameter, chord, tangent, sector, quadrant). The teacher explains each part, defining it and pointing it out on the chart. The teacher also demonstrates drawing some parts on the board.
Pupils’ Activity: Pupils identify the parts on the chart, listen to explanations, and ask questions for clarification.
Learning Point: Pupils can identify and name the different parts of a circle.

Step 4: Concentric and Eccentric Circles

Time: 7 minutes
Teaching Skill: Explanation/Comparison
Teacher’s Activity: The teacher uses another chart or draws on the board to illustrate concentric and eccentric circles. The teacher explains the difference between them, emphasizing the position of their centres. Pupils are encouraged to give examples.
Pupils’ Activity: Pupils observe the illustrations, understand the concepts, and contribute examples.
Learning Point: Pupils can distinguish between and explain concentric and eccentric circles.

Step 5: Importance of Labelling and Neat Presentation

Time: 5 minutes
Teaching Skill: Discussion/Emphasis
Teacher’s Activity: The teacher discusses why neatness and correct labelling are important in technical drawing, explaining how it aids clarity and communication. The teacher emphasizes that accurate technical drawings require precise labelling.
Pupils’ Activity: Pupils listen and contribute to the discussion, understanding the value of neatness.
Learning Point: Pupils appreciate the need for neatness and accurate labelling in technical drawings.

Step 6: Practical Application

Time: 5 minutes
Teaching Skill: Practical/Supervision
Teacher’s Activity: The teacher instructs pupils to draw a circle of a given radius on their drawing sheets and label its parts. The teacher moves around to provide guidance and correct any errors.
Pupils’ Activity: Pupils use their drawing instruments to draw circles and label them as instructed.
Learning Point: Pupils practice drawing and labelling circles, applying the knowledge gained.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define a circle.
Mention any four parts of a circle.
Explain the difference between a radius and a diameter.
What are concentric circles?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definition of a circle, its parts, and the concepts of concentric and eccentric circles. The teacher assigns homework: draw a set of concentric circles and a set of eccentric circles.
Pupils’ Activity: Pupils listen to the summary and note down the homework.
Learning Point: Pupils consolidate their understanding of the lesson and are given tasks to reinforce learning.

Lesson Keywords

Circle – A plane figure bounded by a continuous curved line, equidistant from a central point.
Radius – A line segment from the centre to the circumference of a circle.
Diameter – A line segment passing through the centre and connecting two points on the circumference.
Chord – A line segment connecting any two points on the circumference.
Tangent – A line that touches a circle at exactly one point.
Concentric – Circles sharing the same centre but having different radii.
Eccentric – Circles that do not share the same centre.

Differentiation

For pupils who grasp concepts quickly, they can be challenged to draw more complex arrangements of circles or research the applications of circles in different fields. For pupils needing more support, the teacher will provide one-on-one guidance during practical drawing sessions and simplify explanations using more visual aids.

Note for teachers using this lesson plan

Ensure all drawing instruments are available and in good working condition. Emphasize neatness and accuracy from the beginning. Encourage pupils to practice drawing circles and their parts regularly. Practical demonstration by the teacher is key to effective learning in technical drawing.