Class: Senior Secondary School 2 (SS2 / SSS2)
Term: 2nd Term
Week: 8
Age: 16 years
Duration: 45 minutes
Subject: Basic Electricity
Curriculum Theme: Electrical Measurements
Previous Lesson: Measuring Instruments: Conversion of Moving Coil Instrument Into Ammeter and Voltmeter.
Topic: MEASURING INSTRUMENTS
Subject Matter: Meaning of electrical measurement (definition), measurement of voltage (using voltmeter), measurement of current (using ammeter), measurement of resistance (using ohmmeter)

Specific Objectives

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

Cognitive Domain:

Define electrical measurement.
State the purpose of a voltmeter, ammeter, and ohmmeter.
Explain how each instrument is connected in a circuit.

Affective Domain:

Appreciate the importance of accurate electrical measurements.
Develop an interest in practical electrical work.

Psychomotor Domain:

Correctly connect a voltmeter to measure voltage.
Correctly connect an ammeter to measure current.
Correctly use an ohmmeter (or multimeter) to measure resistance.

Work collaboratively in groups during practical demonstrations.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
NELSON WAEC Basic Electricity for Senior Secondary Schools
https://www.physicsclassroom.com/class/circuits/Lesson-4/Circuit-Symbols-and-Circuit-Diagrams
https://www.fluke.com/en-us/learn/blog/electrical/what-is-a-multimeter

Instructional Materials

The teacher will teach this lesson with the aid of:

Multimeter
Test circuit (with resistors, wires, battery)

Rationale for the Lesson

Understanding electrical measuring instruments enables pupils to diagnose faults, verify circuit operations, and safely work with electrical systems. It helps them to apply theoretical knowledge to practical situations in daily life and future careers.

Prerequisite/Previous Knowledge

Pupils have a basic understanding of electric current, voltage, resistance, and simple electrical circuits.

Lesson Content/Board Summary

MEASURING INSTRUMENTS

Meaning of Electrical Measurement

Electrical measurement is the process of quantifying electrical quantities such as voltage, current, and resistance in an electrical circuit. It is essential for understanding circuit behavior, troubleshooting, and ensuring safe operation.

Measurement of Voltage (Using Voltmeter)

Voltage (V) is the electrical potential difference between two points in a circuit, which drives the current. It is measured in Volts.

Voltmeter: An instrument specifically designed to measure voltage.
Connection: A voltmeter is always connected in parallel across the component or power source whose voltage is to be measured. This means it forms a separate path alongside the component.
Internal Resistance: Voltmeters have a very high internal resistance to ensure that they draw minimal current from the circuit, thus not affecting the circuit’s operation.

Measurement of Current (Using Ammeter)

Current (I) is the rate of flow of electric charge through a conductor. It is measured in Amperes (A).

Ammeter: An instrument used to measure electric current.
Connection: An ammeter is always connected in series with the component through which the current is to be measured. This means the current flows directly through the ammeter.
Internal Resistance: Ammeters have a very low internal resistance to minimize voltage drop across them, ensuring they do not significantly impede the current flow in the circuit.

Measurement of Resistance (Using Ohmmeter)

Resistance (R) is the opposition to the flow of electric current in a circuit. It is measured in Ohms (Ω).

Ohmmeter: An instrument used to measure electrical resistance.
Connection: An ohmmeter is connected across the component whose resistance is to be measured. The circuit must be de-energized (power off) before connecting the ohmmeter, as current from the circuit can damage the instrument.
Multimeter: A versatile instrument that combines the functions of a voltmeter, ammeter, and ohmmeter into a single device. It requires selecting the appropriate function and range before taking a measurement.

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 asks pupils what they think is needed to know if an electrical appliance is working correctly or to find a fault.
Pupils’ Activity: Pupils respond, suggesting things like checking power, or using tools to check.
Learning Point: Pupils are introduced to the concept of electrical measurement and its importance.

Step 2: Meaning of Electrical Measurement

Time: 7 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains the meaning of electrical measurement and why it is important for understanding and troubleshooting circuits.
Pupils’ Activity: Pupils listen attentively and take notes on the definition and importance.
Learning Point: Pupils understand what electrical measurement is and its practical relevance.

Step 3: Measurement of Voltage (Voltmeter)

Time: 8 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains voltage, introduces the voltmeter, demonstrates how to connect it in parallel to measure voltage, and explains its high internal resistance.
Pupils’ Activity: Pupils observe the demonstration, ask questions, and note down how to use a voltmeter.
Learning Point: Pupils learn about voltage measurement and the correct use of a voltmeter.

Step 4: Measurement of Current (Ammeter)

Time: 7 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains current, introduces the ammeter, demonstrates how to connect it in series to measure current, and explains its low internal resistance.
Pupils’ Activity: Pupils observe the demonstration, ask questions, and note down how to use an ammeter.
Learning Point: Pupils learn about current measurement and the correct use of an ammeter.

Step 5: Measurement of Resistance (Ohmmeter)

Time: 7 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains resistance, introduces the ohmmeter (or multimeter in ohmmeter mode), demonstrates how to connect it across a component (with power off), and explains the safety precaution.
Pupils’ Activity: Pupils observe the demonstration, ask questions, and note down how to use an ohmmeter.
Learning Point: Pupils learn about resistance measurement and the safe use of an ohmmeter.

Step 6: Practical Application/Hands-on Activity

Time: 5 minutes
Teaching Skill: Practical Application
Teacher’s Activity: The teacher guides pupils to practice using the multimeter to measure voltage, current, and resistance in a simple test circuit under supervision.
Pupils’ Activity: Pupils, in groups, practice connecting and reading measurements from the multimeter for different quantities.
Learning Point: Pupils gain practical experience in using electrical measuring instruments.

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 electrical measurement?
State the instrument used to measure current and how it is connected in a circuit.
Describe how a voltmeter is connected to measure voltage.
Why must an ohmmeter be connected to a de-energized circuit?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 1 minute
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of accurate and safe use of measuring instruments.
Pupils’ Activity: Pupils listen and confirm their understanding.
Learning Point: Pupils consolidate their knowledge of electrical measuring instruments.

Lesson Keywords

Voltmeter – An instrument used to measure voltage.
Ammeter – An instrument used to measure electric current.
Ohmmeter – An instrument used to measure electrical resistance.
Multimeter – A multi-purpose instrument that measures voltage, current, and resistance.
Series Connection – Components connected end-to-end, so the current flows through each in sequence.
Parallel Connection – Components connected across the same two points, creating alternative paths for current.

Differentiation

For struggling learners, the teacher will provide more one-on-one guidance during the practical session and simplify explanations. Advanced learners will be challenged to explain the internal workings of the instruments or predict readings in more complex circuits.

Note for teachers using this lesson plan

Ensure all electrical connections are safe during practical demonstrations. Emphasize the correct range selection on the multimeter before taking any measurements. Supervise pupils closely during hands-on activities to prevent damage to equipment or injury.