Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 2nd Term
Week: 1
Age: 15 years
Duration: 45 minutes
Subject: Basic Electronics
Curriculum Theme: Basic Electronics
Previous Lesson: .
Topic: ELECTRIC POWER Concept of electric power
Subject Matter: meaning of electric power, power in electric circuits, factors affecting power in a circuit, examples of power use in appliances

Specific Objectives

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

Cognitive Domain:

Define electric power.
State the formulas for calculating electric power in a circuit.
Identify factors that affect electric power in a circuit.
List examples of appliances that use electric power.

Affective Domain:

Appreciate the importance of electric power in daily life.
Show interest in understanding how power is consumed in electrical devices.

Psychomotor Domain:

Calculate simple electric power problems given voltage, current, or resistance.
Identify the power ratings on common electrical appliances.

Participate actively in class discussions about electric power.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology (JSS 1-3).
State Unified Scheme of Work for Basic Electronics SSS 1.
Basic Electronics for Senior Secondary Schools by [Author/Publisher, e.g., A.N. Okoro, Evans Publishers].
https://www.physicsclassroom.com/class/circuits/Lesson-2/Electric-Power
https://www.allaboutcircuits.com/textbook/direct-current/chpt-2/power-in-electric-circuits/

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts illustrating power concepts (e.g., Ohm’s law triangle adapted for power).
Simple circuit examples (diagrams or actual components if available).
Electrical appliances with visible power ratings (e.g., light bulb, electric iron).
Whiteboard and markers.

Rationale for the Lesson

Understanding electric power helps pupils grasp how electrical energy is used and converted in various devices. It enables them to appreciate the importance of power ratings on appliances and how electricity consumption affects daily life.

Prerequisite/Previous Knowledge

Pupils are assumed to have prior knowledge of basic electrical quantities such as voltage, current, and resistance, and an understanding of simple electric circuits.

Lesson Content/Board Summary

ELECTRIC POWER

Meaning of Electric Power

Electric power is the rate at which electrical energy is converted or dissipated into other forms of energy (e.g., heat, light, mechanical energy) in an electric circuit.

The Standard International (SI) unit of electric power is the Watt (W).

Power in Electric Circuits

Power (P) in an electric circuit can be calculated using the following formulas:

P = V × I (Power = Voltage × Current)
P = I² × R (Power = Current² × Resistance)
P = V² / R (Power = Voltage² / Resistance)

Where: P = Power in Watts (W), V = Voltage in Volts (V), I = Current in Amperes (A), R = Resistance in Ohms (Ω).

Factors Affecting Power in a Circuit

The amount of electric power in a circuit is affected by the following factors:

Voltage (V): A higher voltage across a component generally results in higher power dissipation.
Current (I): A larger current flowing through a component generally results in higher power dissipation.
Resistance (R): The relationship with resistance depends on whether voltage or current is constant. For constant voltage, higher resistance means lower power (P=V²/R). For constant current, higher resistance means higher power (P=I²R).

Examples of Power Use in Appliances

Electric power is fundamental to the operation of numerous appliances in homes, schools, and industries. Some common examples include:

Electric Heater: Converts electrical energy into heat energy.
Electric Fan: Converts electrical energy into mechanical energy (for rotation and air movement).
Light Bulb: Converts electrical energy into light energy and some heat.
Television: Converts electrical energy into light and sound energy.
Electric Iron: Converts electrical energy into heat energy for pressing clothes.
Refrigerator: Uses electrical energy to power a compressor for cooling.

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 introduces the new topic by asking pupils what they understand by ‘power’ in general terms, and how electricity makes appliances work.
Pupils’ Activity: Pupils respond to questions and listen attentively to the introduction.
Learning Point: Pupils are reminded of previous knowledge and are prepared for the new topic.

Step 2: Meaning of Electric Power

Time: 10 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines electric power, explains its concept as the rate of energy conversion, and introduces the Watt as its unit. The teacher writes the definition on the board.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and unit of electric power.

Step 3: Power in Electric Circuits

Time: 10 minutes
Teaching Skill: Formula Derivation/Application
Teacher’s Activity: The teacher presents the formulas for calculating electric power (P=VI, P=I²R, P=V²/R), explaining each variable and how these formulas relate to Ohm’s Law. The teacher works through a simple example if time permits.
Pupils’ Activity: Pupils write down the formulas and follow the explanation, attempting to apply them to simple mental checks.
Learning Point: Pupils learn the different formulas for calculating electric power.

Step 4: Factors Affecting Power in a Circuit

Time: 5 minutes
Teaching Skill: Elucidation
Teacher’s Activity: The teacher discusses the factors that influence the amount of power in a circuit, namely voltage, current, and resistance, explaining their relationship based on the power formulas.
Pupils’ Activity: Pupils listen and contribute by identifying how changes in these factors might affect power.
Learning Point: Pupils understand what determines the amount of power in an electric circuit.

Step 5: Examples of Power Use in Appliances

Time: 5 minutes
Teaching Skill: Illustration/Demonstration
Teacher’s Activity: The teacher gives various examples of common electrical appliances and explains how they use electric power, relating it to their function. The teacher may show actual appliances or pictures, pointing out their power ratings.
Pupils’ Activity: Pupils identify appliances they use daily and discuss their power consumption.
Learning Point: Pupils connect the concept of electric power to practical applications and everyday devices.

Step 6: Class Activity/Problem Solving

Time: 5 minutes
Teaching Skill: Application/Problem Solving
Teacher’s Activity: The teacher provides a simple calculation problem (e.g., “A lamp draws 0.5A from a 12V supply. Calculate its power.”) or asks pupils to identify power ratings on given appliance images.
Pupils’ Activity: Pupils attempt to solve the problem individually or in pairs, or identify power ratings.
Learning Point: Pupils practice applying the power formulas and recognizing power ratings.

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 electric power?
State any two formulas for calculating electric power.
Mention two factors that affect power in an electric circuit.
List three examples of appliances that use electric power.

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 briefly summarizes the key points of the lesson on electric power, its calculation, factors, and uses. The teacher then assigns homework, which may include researching power ratings of household appliances.
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their understanding of the lesson.

Lesson Keywords

Electric Power – The rate at which electrical energy is converted or dissipated.
Watt (W) – The SI unit of electric power.
Voltage (V) – The electric potential difference across two points in a circuit.
Current (I) – The flow of electric charge.
Resistance (R) – The opposition to the flow of electric current.

Differentiation

For pupils who grasp concepts quickly, the teacher can provide more complex power calculation problems involving combinations of series and parallel circuits. For pupils needing more support, the teacher can provide simplified notes, focus on one formula at a time, and offer one-on-one guidance or peer tutoring.

Note for teachers using this lesson plan

Ensure that the instructional materials, especially charts and examples, are clear and visible to all pupils. Encourage active participation and practical examples from pupils’ daily experiences to make the concept of electric power more relatable. Emphasize safety precautions when discussing electrical appliances.