Class: Senior Secondary School 1 (SS1 / SSS1)
Term: 1st Term
Week: 9
Age: 15 years
Duration: 45 minutes
Subject: Electrical Installation and Maintenance Work
Curriculum Theme: Technology
Previous Lesson: Cable: Definition, Types and Preparation.
Topic: WORKING DRAWING
Subject Matter: Types of drawing, meaning of electrical symbols, common electrical symbols used in working drawings, drawing practice of basic symbols.

Specific Objectives

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

Cognitive Domain:

Define a working drawing.
Identify and explain different types of drawing.
State the meaning and importance of electrical symbols.
List common electrical symbols used in working drawings.

Affective Domain:

Appreciate the importance of working drawings for clear communication.
Show interest in learning and drawing electrical symbols.

Psychomotor Domain:

Draw at least five basic electrical symbols accurately.

Participate actively in class discussions and drawing practice.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Electrical Installation and Maintenance Work.
State Unified Scheme of Work for Senior Secondary School Electrical Installation and Maintenance Work.
Electrical Installation and Maintenance Work for Senior Secondary Schools by A.O. Okoro.
Basic Electricity and Electronics by T.L. Floyd.
https://www.electricaltechnology.org/2019/07/electrical-electronic-symbols.html
https://www.elexp.com/electrical-symbols-and-their-meaning/

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts showing various types of drawing.
Charts displaying common electrical symbols.
Whiteboard/chalkboard.
Markers/chalk.
Drawing instruments (rulers, pencils, erasers).
Working diagrams of simple electrical installations.

Rationale for the Lesson

This lesson helps pupils understand how technical information is communicated in the electrical field. Learning about working drawings and electrical symbols enables pupils to interpret and create plans for electrical installations, which is essential for safe and correct work.

Prerequisite/Previous Knowledge

Pupils are expected to have basic knowledge of drawing and some common electrical components from their previous lessons.

Lesson Content/Board Summary

Working Drawings and Electrical Symbols

1. Introduction to Working Drawings

A working drawing is a detailed graphical representation that provides all necessary information for the construction or assembly of a component or system. It serves as a visual language for engineers, technicians, and artisans.

2. Types of Drawing

Drawings are categorised based on their application or the field they represent. The following are common types of drawing:

Civil Drawing: These drawings show the layout, dimensions, and structural details of buildings, roads, bridges, and other civil engineering projects. They include architectural, structural, and site plans.
Mechanical Drawing: These drawings illustrate the design, dimensions, and assembly of mechanical parts, machines, and systems. Examples include parts drawings, assembly drawings, and schematic diagrams for mechanical devices.
Electrical Drawing: These drawings show the layout, wiring, components, and connections of electrical circuits and systems. They are used for designing and installing electrical installations in homes, industries, and other structures.

3. Meaning of Electrical Symbols

Electrical symbols are standardised graphical representations used in electrical drawings to denote various electrical components, devices, and functions. They simplify complex circuit diagrams and ensure universal understanding among professionals.

The importance of electrical symbols includes:

They provide a clear and concise way to represent electrical components.
They allow for easy interpretation of electrical diagrams across different regions and languages.
They help in troubleshooting and maintenance of electrical systems.
They ensure consistency and accuracy in electrical installations.

4. Common Electrical Symbols Used in Working Drawings

The following are some common electrical symbols:

Switch (Single Pole): Represents a device used to open or close an electrical circuit.
Socket Outlet (General Purpose): Represents a point where an electrical appliance can be plugged in to draw power.
Lamp/Light Bulb: Represents a device that produces light when electricity passes through it.
Fuse: Represents a safety device that melts and breaks a circuit when current exceeds a safe level.
Circuit Breaker: Represents an automatic device that protects an electrical circuit from damage caused by an overload or short circuit.
Electric Bell: Represents a device that produces a ringing sound when activated.
Earth/Ground: Represents a connection to the general mass of the earth for safety and fault protection.

5. Drawing Practice of Basic Symbols

Regular practice in drawing electrical symbols helps in familiarisation and improves accuracy when creating or interpreting electrical working drawings.

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 reviews the previous lesson briefly. The teacher then asks pupils what they understand by ‘drawing’ and its importance in everyday life, leading to the topic of working drawings.
Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively.
Learning Point: Pupils are prepared for the new lesson and connect it to their prior knowledge.

Step 2: Presentation of Types of Drawing

Time: 10 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains what a working drawing is and then discusses the different types of drawing, specifically civil, mechanical, and electrical drawings, using the charts to illustrate. The teacher highlights the distinct purpose of each type.
Pupils’ Activity: Pupils observe the charts, listen to the explanations, and ask questions for clarity.
Learning Point: Pupils understand the concept of working drawings and can identify different types.

Step 3: Explanation of Electrical Symbols

Time: 7 minutes
Teaching Skill: Definition/Clarification
Teacher’s Activity: The teacher defines electrical symbols and explains their importance in electrical working drawings, emphasising standardization and clear communication.
Pupils’ Activity: Pupils listen and note down the definition and importance of electrical symbols.
Learning Point: Pupils understand the meaning and significance of electrical symbols.

Step 4: Display and Discussion of Common Electrical Symbols

Time: 8 minutes
Teaching Skill: Demonstration/Visualisation
Teacher’s Activity: The teacher displays charts showing common electrical symbols. For each symbol, the teacher explains its name, what it represents, and its function in a circuit.
Pupils’ Activity: Pupils observe the charts, identify the symbols, and note their meanings and functions.
Learning Point: Pupils can recognise and state the meaning of common electrical symbols.

Step 5: Teacher Demonstration of Drawing Basic Symbols

Time: 5 minutes
Teaching Skill: Demonstration/Modeling
Teacher’s Activity: The teacher demonstrates on the whiteboard how to draw 3-4 basic electrical symbols clearly and accurately, explaining the correct strokes and proportions.
Pupils’ Activity: Pupils observe the teacher’s demonstration carefully.
Learning Point: Pupils learn the correct technique for drawing electrical symbols.

Step 6: Pupils Practice Drawing Symbols

Time: 5 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher instructs pupils to practice drawing some of the basic symbols in their notebooks. The teacher moves around the classroom, providing guidance and correction where needed.
Pupils’ Activity: Pupils practice drawing the electrical symbols as demonstrated by the teacher.
Learning Point: Pupils improve their psychomotor skills in drawing electrical symbols.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

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

What is a working drawing?
Mention two types of drawing and briefly explain them.
What is the meaning of an electrical symbol?
List three common electrical symbols and state what each represents.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarises the key points of the lesson, reiterating the importance of working drawings and electrical symbols. The teacher assigns homework for pupils to draw ten common electrical symbols and identify their names.
Pupils’ Activity: Pupils listen to the summary and note down the homework.
Learning Point: Pupils have a clear understanding of the lesson and know their assignment.

Lesson Keywords

Working Drawing – A detailed graphical representation providing information for construction or assembly.
Civil Drawing – Drawings for buildings, roads, and other civil structures.
Mechanical Drawing – Drawings for machine parts, assemblies, and mechanical systems.
Electrical Drawing – Drawings for electrical circuits, wiring, and installations.
Electrical Symbols – Standardised graphical representations of electrical components.
Switch – A device to open or close an electrical circuit.
Socket Outlet – A point for connecting electrical appliances.
Fuse – A safety device that protects circuits from overcurrent.

Differentiation

The teacher will provide additional support to pupils who struggle with drawing by offering one-on-one guidance and simplified examples. Advanced pupils will be encouraged to research and draw more complex electrical symbols.

Note for teachers using this lesson plan

Ensure that the charts showing electrical symbols are clear, visible, and contain symbols relevant to the local curriculum. Encourage active participation and provide ample opportunity for pupils to practice drawing, as this is a practical skill.