Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: Second Term
Week: 2
Age: 15 years
Duration: 45 minutes
Subject: Basic Electronics
Curriculum Theme: Basic Electronics
Previous Lesson: Electric Power: Concept and Meaning.
Topic: ELECTRIC POWER
Subject Matter: Relationship between power, current, and voltage.

Specific Objectives

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

Cognitive Domain:

Define electric power.
State the relationship between electric power, current, and voltage.
Recall the formula for calculating electric power (P = I x V).

Affective Domain:

Appreciate the importance of electric power in everyday appliances.
Show willingness to solve problems involving electric power calculations.

Psychomotor Domain:

Calculate the electric power in a given circuit using the formula.
Interpret the results of power calculations.

Work collaboratively to solve problems related to electric power.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Basic Technology.
State Unified Scheme of Work for Basic Electronics (SSS 1).
Basic Electronics for Senior Secondary Schools, Book 1.

Instructional Materials

The teacher will teach this lesson with the aid of:

Calculators
Charts displaying power formulas
Whiteboard and markers

Rationale for the Lesson

Understanding electric power helps pupils to know how much energy electrical appliances consume and how to use them safely. This knowledge is important for managing electricity use at home and for understanding electrical systems around them.

Prerequisite/Previous Knowledge

Pupils are expected to have basic knowledge of electric current, voltage, and simple electrical circuits from previous lessons.

Lesson Content/Board Summary

Electric Power

Definition of Electric Power

Electric power is the rate at which electrical energy is transferred or consumed in an electric circuit. It measures how quickly work is done by electricity.

Relationship between Power, Current, and Voltage

Electric power is directly related to both the current flowing through a circuit and the voltage across the circuit. A higher current or higher voltage generally means higher power.

Formula for Electric Power

The most common formula for calculating electric power in a DC circuit is:

P = I x V

Where:

P = Power (measured in Watts, W)
I = Current (measured in Amperes, A)
V = Voltage (measured in Volts, V)

Calculating Electric Power in a Given Circuit

To calculate electric power, multiply the current by the voltage.

Example:

A light bulb draws a current of 0.5 A when connected to a 220 V supply. Calculate the power consumed by the bulb.

Solution:

Given: Current (I) = 0.5 A, Voltage (V) = 220 V
Formula: P = I x V
P = 0.5 A x 220 V
P = 110 W

Interpreting Power Results

The calculated power value indicates the rate at which an electrical device uses energy. A higher wattage means the device consumes more energy per second. For example, a 100 W bulb is brighter and uses more power than a 60 W bulb.

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 what they understand by electric current and voltage. The teacher then introduces the topic, Electric Power, and states the objectives for the lesson.
Pupils’ Activity: Pupils respond to questions about current and voltage and listen attentively to the introduction.
Learning Point: Pupils recall previous knowledge and are prepared for the new topic.

Step 2: Explanation of Electric Power

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines electric power as the rate at which electrical energy is used or transferred. The teacher explains that power is what makes appliances work at a certain rate.
Pupils’ Activity: Pupils listen and take notes, asking questions for clarification.
Learning Point: Pupils understand the definition of electric power.

Step 3: Relationship between Power, Current, and Voltage

Time: 8 minutes
Teaching Skill: Elucidation/Connection
Teacher’s Activity: The teacher explains how power is connected to current and voltage. The teacher emphasizes that power increases with both current and voltage. The teacher uses the chart to illustrate this relationship.
Pupils’ Activity: Pupils observe the chart, listen to the explanation, and ask questions.
Learning Point: Pupils understand that power depends on current and voltage.

Step 4: Formula for Electric Power (P = I x V)

Time: 7 minutes
Teaching Skill: Formula Presentation
Teacher’s Activity: The teacher presents the formula P = I x V on the board and explains each symbol and its unit. The teacher ensures pupils understand how to identify current and voltage in a problem.
Pupils’ Activity: Pupils write down the formula and units, asking for clarification on any part they do not understand.
Learning Point: Pupils learn the formula for calculating electric power.

Step 5: Calculating Electric Power

Time: 8 minutes
Teaching Skill: Demonstration/Application
Teacher’s Activity: The teacher works through the example provided in the lesson content on the board, demonstrating step-by-step how to use the formula P = I x V to calculate power. The teacher encourages pupils to use their calculators.
Pupils’ Activity: Pupils follow the teacher’s steps, perform calculations with their calculators, and solve similar problems if given.
Learning Point: Pupils learn to apply the power formula to solve problems.

Step 6: Interpreting Power Results

Time: 3 minutes
Teaching Skill: Interpretation
Teacher’s Activity: The teacher explains what the calculated power value means in practical terms, relating it to how much energy an appliance uses. For instance, a higher wattage means more energy consumption.
Pupils’ Activity: Pupils listen and contribute examples of appliances with different power ratings.
Learning Point: Pupils understand the practical meaning of power values.

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 power.
State the relationship between power, current, and voltage.
Write down the formula for electric power.
Calculate the power consumed by a device that draws 2 A of current from a 12 V battery.

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/Consolidation
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definition of power, its relationship with current and voltage, and the formula. The teacher assigns homework: find the power rating of three different electrical appliances at home.
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their understanding of electric power.

Lesson Keywords

Electric Power – The rate at which electrical energy is transferred or consumed.
Current – The flow of electric charge.
Voltage – The electrical potential difference between two points.
Watt (W) – The unit of electric power.
Ampere (A) – The unit of electric current.
Volt (V) – The unit of electric voltage.

Differentiation

For pupils who grasp concepts quickly, the teacher can provide additional complex problems involving rearrangements of the power formula or introduce other power formulas (P = I²R, P = V²/R). For pupils who need more support, the teacher will provide simplified examples and offer one-on-one guidance during calculation practice.

Note for teachers using this lesson plan

Ensure that pupils understand the units for current, voltage, and power, as correct unit usage is important in calculations. Encourage pupils to show all their working steps when solving problems. Practical examples of appliances and their power ratings can help make the lesson more relatable.