Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 1st Term
Week: 4
Age: 15 years
Duration: 45 minutes
Subject: Electrical Installation and Maintenance Work
Curriculum Theme: Technology
Previous Lesson: Hazards in Electrical Installation Work: Causes and Prevention.
Topic: MEASURING Types and Uses of Measuring Instrument
Subject Matter: Meaning of measurement in electrical work, types of measuring instruments, uses of measuring instruments, introduction to ohmmeter and what it measures.

Specific Objectives

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

Cognitive Domain:

Define measurement in electrical work.
Identify different types of measuring instruments used in electrical work.
State the uses of various measuring instruments.
Explain what an ohmmeter measures.

Affective Domain:

Show interest in observing and identifying measuring instruments.
Appreciate the importance of accurate measurement in electrical installations.

Psychomotor Domain:

Handle basic measuring instruments safely (e.g., ohmmeter).
Demonstrate the basic use of an ohmmeter to check continuity or resistance.

Collaborate with peers in identifying and discussing measuring instruments.
Adhere to safety guidelines when using electrical measuring instruments.

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 Schools.
Basic Electricity and Electronics for Senior Secondary Schools by E.J. Akpan.

Instructional Materials

The teacher will teach this lesson with the aid of:

An ohmmeter.
Charts showing different types of measuring instruments (e.g., voltmeter, ammeter, multimeter).
Pictures of various electrical measuring instruments.

Rationale for the Lesson

This lesson helps pupils understand the essential role of measurement in electrical work, which is fundamental for safety and proper functioning of electrical systems. Knowledge of different instruments and their uses enables pupils to perform basic electrical tasks accurately and diagnose simple faults in daily life.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of electricity, including concepts like current, voltage, and resistance, from their previous lessons.

Lesson Content/Board Summary

MEASURING INSTRUMENTS: TYPES AND USES

Meaning of Measurement in Electrical Work

Measurement in electrical work is the process of determining the size, quantity, or degree of an electrical property such as voltage, current, or resistance using specific instruments. Accurate measurement ensures safety, efficiency, and correct functioning of electrical installations.

Types of Measuring Instruments

The following are common types of measuring instruments used in electrical work:

Ammeter: Used to measure electric current in amperes. It is connected in series with the circuit.
Voltmeter: Used to measure electric potential difference (voltage) in volts. It is connected in parallel across the component.
Ohmmeter: Used to measure electrical resistance in ohms. It is used when the circuit is de-energized.
Multimeter (AVO meter): A versatile instrument that combines the functions of an ammeter, voltmeter, and ohmmeter. It can measure current, voltage, and resistance.
Wattmeter: Used to measure electric power in watts.
Energy Meter: Used to measure electrical energy consumption over a period, usually in kilowatt-hours (kWh).

Uses of Measuring Instruments

Measuring instruments are used for various purposes in electrical work:

To verify the presence and value of voltage in a circuit.
To determine the amount of current flowing through a circuit or component.
To check the resistance of components, wires, or circuits for continuity or shorts.
To test for open circuits, short circuits, and ground faults.
To ensure that electrical installations meet specified standards and regulations.
To troubleshoot and diagnose faults in electrical systems.

Introduction to Ohmmeter

An ohmmeter is an electrical instrument specifically designed to measure electrical resistance. Resistance is the opposition to the flow of electric current, measured in ohms (Ω).

An ohmmeter works by sending a small current through the component or circuit being tested and measuring the voltage drop across it. Using Ohm’s Law (V=IR), it then calculates and displays the resistance.

An ohmmeter measures:

The resistance of a conductor or component.
Continuity in a circuit (a very low resistance indicates continuity, while infinite resistance indicates an open circuit).
The presence of short circuits (very low resistance where it should be high).

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, reviews the previous lesson briefly, and then asks pupils what they understand by “measurement” in general terms. The teacher then introduces the topic by stating that just as we measure length with a tape, we also measure electrical properties with special tools.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils are prepared for the new lesson and connect it to general knowledge.

Step 2: Meaning of Measurement in Electrical Work

Time: 8 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines measurement in electrical work, explaining why it is important for safety and efficiency. The teacher uses simple examples.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and importance of measurement in electrical work.

Step 3: Types of Measuring Instruments

Time: 10 minutes
Teaching Skill: Identification/Listing
Teacher’s Activity: The teacher displays charts or pictures of various measuring instruments (ammeter, voltmeter, ohmmeter, multimeter) and names them. The teacher briefly explains what each instrument measures.
Pupils’ Activity: Pupils observe the displayed instruments, identify them, and note down their names.
Learning Point: Pupils can identify and name different electrical measuring instruments.

Step 4: Uses of Measuring Instruments

Time: 7 minutes
Teaching Skill: Elucidation/Application
Teacher’s Activity: The teacher explains the general uses of measuring instruments in electrical work, linking them to safety, troubleshooting, and quality control.
Pupils’ Activity: Pupils listen, contribute ideas, and note down the uses.
Learning Point: Pupils understand why and how these instruments are applied in practice.

Step 5: Introduction to Ohmmeter

Time: 5 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher specifically introduces the ohmmeter, displaying a real one if available. The teacher explains what it measures (resistance, continuity) and briefly demonstrates how it is used to check a simple wire for continuity.
Pupils’ Activity: Pupils observe the ohmmeter, ask questions about its function, and watch the demonstration.
Learning Point: Pupils gain specific knowledge about the ohmmeter and its basic operation.

Step 6: Class Discussion and Questioning

Time: 5 minutes
Teaching Skill: Question and Answer
Teacher’s Activity: The teacher facilitates a brief class discussion, asking pupils to recall the names and uses of instruments discussed. The teacher clarifies any misconceptions.
Pupils’ Activity: Pupils actively participate, answer questions, and consolidate their understanding.
Learning Point: Pupils reinforce their learning through active recall and peer interaction.

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 measurement in electrical work.
Mention three types of electrical measuring instruments.
State one use of an ammeter.
What does an ohmmeter measure?

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, emphasizing the importance of accurate measurement and the correct use of instruments. The teacher assigns homework: “List five reasons why accurate measurement is important in electrical installation work.”
Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.
Learning Point: Pupils recall the main aspects of the lesson and are given an opportunity for further practice.

Lesson Keywords

Measurement – The process of determining the size or quantity of an electrical property.
Ammeter – An instrument used to measure electric current.
Voltmeter – An instrument used to measure electric potential difference (voltage).
Ohmmeter – An instrument used to measure electrical resistance.
Multimeter – A multi-purpose instrument that measures current, voltage, and resistance.
Resistance – The opposition to the flow of electric current, measured in ohms.

Differentiation

The teacher will provide additional support to struggling pupils through simplified explanations and one-on-one guidance. Advanced pupils will be encouraged to research more complex measuring instruments or advanced applications of the discussed instruments.

Note for teachers using this lesson plan

Teachers should ensure that actual measuring instruments are available for demonstration. Emphasize safety precautions when handling and connecting electrical measuring instruments. Encourage practical activities where possible, even if simulated, to enhance understanding.