Class: Senior Secondary School 1 (SS1 / SSS 1)
Term: 3rd Term
Week: 11
Age: 15 years
Duration: 45 minutes
Subject: Radio, Tv & Electronics
Curriculum Theme: Trade
Previous Lesson: Electronic Measuring Instruments: Multimeter Uses And Safety.
Topic: ELECTRIC MEASURING INSTRUMENTS
Subject Matter: Reading active components, Reading passive components, Correct multimeter usage

Specific Objectives

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

Cognitive Domain:

Define electric measuring instruments.
Identify active and passive components.
State the functions of a multimeter.
Explain how to read resistance and continuity with a multimeter.

Affective Domain:

Appreciate the importance of accurate measurements in electronics.
Show care when handling electric measuring instruments.
Develop an interest in practical electronics.

Psychomotor Domain:

Connect a multimeter correctly to a circuit component.
Accurately read the values of passive components (e.g., resistors).
Perform basic checks on active components (e.g., diodes) using a multimeter.

Collaborate with peers during practical exercises.
Communicate findings clearly during measurements.

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 Radio, TV & Electronics (SSS 1).
Basic Electricity and Electronics for Senior Secondary Schools by [Author/Publisher, e.g., Evans].

Instructional Materials

The teacher will teach this lesson with the aid of:

Multimeter (digital and/or analog).
Circuit board with various active and passive components (resistors, capacitors, diodes, transistors).
Connecting wires.

Rationale for the Lesson

This lesson helps pupils understand how to use instruments to measure electrical properties, which is important for troubleshooting and repairing electronic devices. Knowing how to correctly use these tools enables pupils to work safely and accurately with electronic components in real-world applications.

Prerequisite/Previous Knowledge

Pupils are expected to have a basic understanding of electricity, simple circuits, and common electronic components from previous lessons.

Lesson Content/Board Summary

ELECTRIC MEASURING INSTRUMENTS

Definition of Electric Measuring Instruments

Electric measuring instruments are devices used to measure electrical quantities like voltage, current, resistance, and continuity in electrical and electronic circuits. They help technicians analyze, troubleshoot, and repair electronic systems.

Types of Electric Measuring Instruments (Multimeter)

While specific instruments exist for each measurement (e.g., voltmeter, ammeter, ohmmeter), a multimeter combines several functions into one device. Multimeters can be:

Analog Multimeter: Uses a needle to indicate readings on a scale.
Digital Multimeter (DMM): Displays readings numerically on an LCD screen.

Active and Passive Components

Electronic components are broadly classified into active and passive types:

Active Components: These are components that can control or amplify electric current. They typically require an external power source to function.
Examples of active components include:
- Transistors
- Diodes
- Integrated Circuits (ICs)
Passive Components: These are components that cannot control or amplify electric current. They do not require an external power source but can dissipate, store, or resist energy.
Examples of passive components include:
- Resistors
- Capacitors
- Inductors

Reading Passive Components

The following are ways to read passive components using a multimeter:

Resistors:
- Set the multimeter to the Ohms (Ω) range.
- Connect the multimeter probes across the resistor terminals.
- Read the resistance value displayed on the meter.
- For continuity check, set to continuity mode (often with a buzzer icon). A beep indicates a continuous path (very low resistance).
Capacitors (Basic Check):
- To check for a shorted or open capacitor, set the multimeter to a high resistance range (e.g., 20kΩ or 200kΩ).
- For electrolytic capacitors, connect the red probe to the positive terminal and the black probe to the negative terminal. The reading should start low and gradually increase, then stabilize. A constant low reading indicates a short, while no reading (open circuit) indicates the capacitor is open.

Reading Active Components (Basic Checks)

The following are ways to perform basic checks on active components using a multimeter:

Diodes:
- Set the multimeter to diode test mode (often indicated by a diode symbol).
- Connect the red probe to the anode and the black probe to the cathode (forward bias): A voltage drop (e.g., 0.5V-0.7V for silicon diodes) should be displayed.
- Reverse the probes (reverse bias): The display should show ‘OL’ (open loop) or a very high resistance, indicating no current flow. If it reads low in both directions, the diode is shorted. If it reads ‘OL’ in both directions, the diode is open.

Correct Multimeter Usage

The following are important steps for correct multimeter usage:

Select the correct function: Always choose the appropriate measurement (voltage, current, resistance, continuity, diode test) before connecting the probes.
Select the correct range: Start with a higher range than the expected value and reduce it if necessary to get an accurate reading.
Connect probes correctly: Typically, the red probe connects to the ‘VΩmA’ or ‘VΩ’ jack, and the black probe connects to the ‘COM’ jack. For current measurements, the red probe might go to a dedicated ‘mA’ or ‘A’ jack.
Ensure power is off for resistance/continuity: Always disconnect power from the circuit when measuring resistance or continuity to prevent damage to the meter or component.
Avoid touching metal tips: Do not touch the metal tips of the probes while measuring to prevent electric shock or inaccurate readings.
Observe polarity: For DC voltage and current measurements, ensure correct polarity to get a positive reading.

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 if they know how electricians or technicians find out if a wire is broken or if a component is working. The teacher then introduces the topic: Electric Measuring Instruments, emphasizing their importance in electronics.
Pupils’ Activity: Pupils respond to the questions and listen attentively to the introduction.
Learning Point: Pupils are introduced to the concept of electric measuring instruments and their relevance.

Step 2: Explanation of Electric Measuring Instruments and Multimeter

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher defines electric measuring instruments and introduces the multimeter as a versatile tool. The teacher displays a multimeter (digital and/or analog) and points out its main parts (display, function switch, input jacks).
Pupils’ Activity: Pupils listen, observe the multimeter, and ask questions for clarification.
Learning Point: Pupils understand what electric measuring instruments are and identify the multimeter as a key tool.

Step 3: Identification of Active and Passive Components

Time: 7 minutes
Teaching Skill: Explanation/Identification
Teacher’s Activity: The teacher explains the difference between active and passive components, providing examples for each. The teacher shows actual samples of resistors, capacitors, diodes, and transistors on the circuit board.
Pupils’ Activity: Pupils identify the components and classify them as active or passive.
Learning Point: Pupils can differentiate between active and passive electronic components.

Step 4: Demonstration of Reading Passive Components

Time: 8 minutes
Teaching Skill: Demonstration/Practical
Teacher’s Activity: The teacher demonstrates how to use the multimeter to measure the resistance of a resistor and perform a continuity check on a wire. The teacher also shows a basic check for a capacitor.
Pupils’ Activity: Pupils observe carefully, noting the settings and connections.
Learning Point: Pupils learn the practical steps for measuring resistance and checking continuity/capacitors.

Step 5: Demonstration of Reading Active Components (Basic Checks)

Time: 7 minutes
Teaching Skill: Demonstration/Practical
Teacher’s Activity: The teacher demonstrates how to perform a basic diode test using the multimeter, showing both forward and reverse bias readings.
Pupils’ Activity: Pupils observe the demonstration and understand the significance of the readings.
Learning Point: Pupils learn how to perform a basic test for active components like diodes.

Step 6: Demonstration of Correct Multimeter Usage

Time: 6 minutes
Teaching Skill: Demonstration/Safety
Teacher’s Activity: The teacher emphasizes the importance of selecting the correct function and range, proper probe connection, ensuring power is off for resistance measurements, and safety precautions (e.g., not touching metal tips).
Pupils’ Activity: Pupils pay attention to the safety guidelines and correct usage procedures.
Learning Point: Pupils understand the proper and safe way to use a multimeter.

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 electric measuring instruments.
Mention two examples of active components and two examples of passive components.
State two functions of a multimeter.
Explain how you would measure the resistance of a resistor using a multimeter.
List three important precautions to observe when using a multimeter.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 0 minutes
Teaching Skill: Summarization
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the importance of electric measuring instruments and correct usage in electronics.
Pupils’ Activity: Pupils listen to the summary and prepare for the next lesson.
Learning Point: Pupils consolidate their understanding of electric measuring instruments.

Lesson Keywords

Multimeter – An electronic measuring instrument that combines several measurement functions in one unit.
Active Components – Electronic components that can control or amplify electric current, requiring an external power source.
Passive Components – Electronic components that cannot control or amplify electric current, but can dissipate, store, or resist energy.
Resistance – The opposition to the flow of electric current, measured in Ohms (Ω).
Continuity – The presence of a complete path for current flow in a circuit.

Differentiation

For pupils who grasp concepts quickly, the teacher can provide more complex components for measurement or challenge them to troubleshoot a simple faulty circuit. For pupils who need more support, the teacher will provide closer supervision during practical demonstrations and offer simplified components for initial practice, focusing on one measurement at a time.

Note for teachers using this lesson plan

Ensure that all multimeters are in good working condition and that components are clearly labeled. Emphasize safety precautions, especially when handling components that might have been connected to power. Encourage hands-on practice, as this subject is best learned through practical application.