Class: Senior Secondary School 2 (SS2 / SSS2)
Term: 2nd Term
Week: 6
Age: 16 years
Duration: 45 minutes
Subject: Basic Electricity
Curriculum Theme: Electrical Measurements
Previous Lesson: AC Motors: Domestic and Industrial Application of AC Motors.
Topic: MEASURING INSTRUMENTS
Subject Matter: Meaning of measuring instruments (definition), identification of electrical measuring instruments (ammeter, voltmeter, ohmmeter), operational range of measuring instruments (minimum and maximum readings).

Specific Objectives

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

Cognitive Domain:

Define electrical measuring instruments.
Identify common electrical measuring instruments.
State the purpose of an ammeter, voltmeter, and ohmmeter.
Explain the importance of the operational range of measuring instruments.

Affective Domain:

Appreciate the importance of using appropriate measuring instruments in electrical work.
Show interest in handling electrical measuring instruments safely.

Psychomotor Domain:

Properly handle an ammeter, voltmeter, and multimeter.
Read the minimum and maximum scales on given instruments.

Work cooperatively during practical demonstrations involving electrical instruments.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
New School Physics for Senior Secondary Schools by M.W. Anyakoha

Instructional Materials

The teacher will teach this lesson with the aid of:

Ammeter
Voltmeter
Multimeter
Connecting wires
Dry cell/battery
Resistor

Rationale for the Lesson

This lesson enables pupils to understand how electrical quantities are measured. It helps them identify and correctly use common electrical measuring instruments, which is essential for practical electrical work and safety.

Prerequisite/Previous Knowledge

Pupils have prior knowledge of basic electrical quantities such as current, voltage, and resistance.

Lesson Content/Board Summary

MEASURING INSTRUMENTS

Meaning of Measuring Instruments

Measuring instruments are devices used to quantify or determine the value of a physical quantity. In electricity, they are used to measure electrical quantities like current, voltage, and resistance.

Identification of Electrical Measuring Instruments

The following are common electrical measuring instruments:

Ammeter: An instrument used to measure electric current in a circuit. It is always connected in series with the component through which the current is to be measured. The unit of current is Ampere (A).
Voltmeter: An instrument used to measure potential difference (voltage) between two points in a circuit. It is always connected in parallel across the component whose voltage is to be measured. The unit of voltage is Volt (V).
Ohmmeter: An instrument used to measure electrical resistance. It is typically used when the circuit is dead (not powered). The unit of resistance is Ohm (Ω).
Multimeter: A versatile instrument that combines the functions of an ammeter, voltmeter, and ohmmeter, and sometimes other measurement functions, into a single unit. It can be set to measure different electrical quantities and ranges.

Operational Range of Measuring Instruments

The operational range of a measuring instrument refers to the minimum and maximum values that the instrument can accurately measure. Instruments are designed to operate within specific limits. It is important to:

Select an instrument with a range appropriate for the expected measurement to avoid damaging the instrument.
Ensure the reading falls within the calibrated scale for accuracy.

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 recall basic electrical quantities they have learned. The teacher then introduces the topic by asking how these quantities can be measured.
Pupils’ Activity: Pupils respond to the questions and listen attentively.
Learning Point: Pupils recall previous knowledge and are introduced to the lesson topic.

Step 2: Meaning of Measuring Instruments

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher explains the meaning of measuring instruments and specifically defines electrical measuring instruments, relating them to the measurement of current, voltage, and resistance.
Pupils’ Activity: Pupils listen and copy the definition into their notebooks.
Learning Point: Pupils understand what measuring instruments are and their purpose in electricity.

Step 3: Identification of Ammeter

Time: 7 minutes
Teaching Skill: Demonstration/Identification
Teacher’s Activity: The teacher displays an ammeter, explains its symbol, how it is connected in a circuit (series), and its unit of measurement (Ampere). The teacher may demonstrate a simple connection.
Pupils’ Activity: Pupils observe the ammeter, ask questions, and note its characteristics.
Learning Point: Pupils identify an ammeter and understand its function and connection method.

Step 4: Identification of Voltmeter

Time: 7 minutes
Teaching Skill: Demonstration/Identification
Teacher’s Activity: The teacher displays a voltmeter, explains its symbol, how it is connected in a circuit (parallel), and its unit of measurement (Volt). The teacher may demonstrate a simple connection.
Pupils’ Activity: Pupils observe the voltmeter, ask questions, and note its characteristics.
Learning Point: Pupils identify a voltmeter and understand its function and connection method.

Step 5: Identification of Ohmmeter/Multimeter

Time: 6 minutes
Teaching Skill: Demonstration/Identification
Teacher’s Activity: The teacher displays an ohmmeter or the ohmmeter function on a multimeter, explains its purpose (measuring resistance), and its unit (Ohm). The teacher also explains the versatility of a multimeter.
Pupils’ Activity: Pupils observe the instruments and note their functions.
Learning Point: Pupils identify an ohmmeter/multimeter and understand its use for measuring resistance.

Step 6: Operational Range of Measuring Instruments

Time: 6 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains the concept of operational range (minimum and maximum readings) for measuring instruments and emphasizes the importance of selecting the correct range to ensure accuracy and prevent damage.
Pupils’ Activity: Pupils listen, observe the scales on the instruments, and ask questions for clarification.
Learning Point: Pupils understand the importance of the operational range of 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 are electrical measuring instruments?
Name three common electrical measuring instruments.
How is an ammeter connected in a circuit, and what does it measure?
Explain the importance of an instrument’s operational range.

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 importance of measuring instruments in electricity. The teacher assigns homework for pupils to draw and label the symbols for ammeter, voltmeter, and ohmmeter.
Pupils’ Activity: Pupils listen to the summary and copy the homework.
Learning Point: Pupils consolidate their understanding and receive an assignment.

Lesson Keywords

Ammeter – An instrument used to measure electric current.
Voltmeter – An instrument used to measure potential difference.
Ohmmeter – An instrument used to measure electrical resistance.
Multimeter – A multi-purpose instrument for measuring current, voltage, and resistance.
Operational Range – The minimum and maximum values an instrument can measure accurately.

Differentiation

For pupils who grasp concepts quickly, the teacher can challenge them to explain how a multimeter selects its range. For pupils who need more support, the teacher will provide closer supervision during instrument identification and reading exercises, offering individual explanations and hands-on guidance.

Note for teachers using this lesson plan

Ensure all electrical instruments are in good working condition and demonstrate safe handling practices. Emphasize the correct connection methods for ammeters (series) and voltmeters (parallel) as this is a common area of confusion for pupils. Encourage pupils to carefully observe the scales and ranges on the instruments.