Class: Junior Secondary School 3 (JSS3, JSS 3)
Term: 2nd Term
Week: 1
Age: 14 years
Duration: 45 minutes
Subject: Mathematics
Curriculum Theme: Mathematics
Previous Lesson:
Topic: Change Of Subject Of Formula
Subject Matter: Changing the subject of a formula, Simplifying expression by substituting in formula..

Specific Objectives

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

Cognitive Domain:
(a) Explain the concept of a formula and the meaning of the subject of a formula.
(b) Change the subject of simple and compound formulae correctly.
Affective Domain:
(a) Demonstrate confidence in manipulating algebraic expressions.
(b) Show interest in solving problems involving change of subject of formula.
Psychomotor Domain:
(a) Perform algebraic operations such as adding, subtracting, and dividing to rearrange formulae.
(b) Substitute values accurately into formulae after rearranging.
Social Domain:
(a) Work collaboratively in solving rearrangement problems.
(b) Communicate steps clearly when explaining solutions to peers.

Reference Materials

The following resources was used in planning this lesson:

9 Years Basic Education Curriculum
Lagos State Unified Scheme of work for Junior Secondary Schools
Wikipedia – Formula
Relevant Textbooks

Instructional Materials

The teacher will teach this lesson with the aid of:

Algebraic charts
Formula manipulation flashcards
Whiteboard and markers
Worked example sheets
Projected steps for rearranging formulae

Rationale for the Lesson

Changing the subject of a formula improves students’ algebraic reasoning and prepares them for advanced mathematical problem-solving.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of algebraic expressions, simple equations, and arithmetic operations.

Lesson Content/Board Summary

Lesson Content

Changing the Subject of a Formula for JSS 3

Meaning of Formula and Subject

A formula is a mathematical rule that shows the relationship between two or more quantities. The subject of the formula is the variable that has been isolated and expressed in terms of other variables.
The following are key points about formula and subject:

A subject is the variable standing alone on one side of the formula.
Changing the subject means rearranging the formula to make another variable the main focus.
Rearrangement must follow correct algebraic steps to maintain equality.

2. Basic Steps in Changing the Subject

Changing the subject of a formula involves applying inverse operations to isolate the required variable.
The following are the steps involved:

Identify the variable to become the new subject.
Use inverse operations to shift other terms across the equality sign.
Simplify the resulting expression if necessary.
Ensure the new variable stands alone on one side of the formula.

3. Examples of Changing the Subject

Examples are:

From ( A = l times b ), make ( b ) the subject:
( b = frac{A}{l} ).
From ( v = u + at ), make ( t ) the subject:
( t = frac{v – u}{a} ).
From ( P = 2(l + b) ), make ( l ) the subject:
( l = frac{P}{2} – b ).

4. Substitution in Formula After Changing Subject

After rearranging a formula, values may be substituted to compute results.
Examples include:

If ( A = l times b ) and ( b = frac{A}{l} ), substitute ( A = 24 ), ( l = 6 ):
( b = frac{24}{6} = 4 ).
If ( v = u + at ) and ( t = 3 ), ( u = 5 ), ( a = 2 ):
( v = 5 + (2 times 3) = 11 ).

Teaching Methods/Instructional Techniques

Discussion, Lecture, Explanation, Demonstration, Guided Practice, Group Work.

Instructional Procedures

To deliver this lesson, the teacher will adopt the following steps:

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher displays a chart showing common mathematical formulae and asks pupils what they observe about how variables relate to each other.
Pupils’ Activity: Pupils respond by identifying variables and equations.
Learning Point: Pupils recall that formulae show relationships between quantities.

Step 2: Meaning of Formula and Subject

Time: 7 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher explains the meaning of a formula and identifies the subject using simple examples.
Pupils’ Activity: Pupils listen and identify the subject in given examples.
Learning Point: Pupils understand the concept of a subject in a formula.

Step 3: Steps in Changing the Subject

Time: 10 minutes
Teaching Skill: Demonstration
Teacher’s Activity: The teacher demonstrates how to isolate a variable step-by-step using examples from the board summary.
Pupils’ Activity: Pupils follow the steps and ask questions for clarification.
Learning Point: Pupils learn the correct steps for rearranging formulae.

Step 4: Examples and Substitution

Time: 10 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher solves more examples, then gives pupils similar problems to solve in pairs.
Pupils’ Activity: Pupils work in pairs to rearrange formulae and substitute values.
Learning Point: Pupils develop proficiency in formula manipulation and substitution.

Step 5: Note-Taking

Time: 3 minutes
Teaching Skill: Reinforcement
Teacher’s Activity: The teacher instructs pupils to copy the board summary.
Pupils’ Activity: Pupils write the notes in their exercise books.
Learning Point: Pupils capture key points for future study.

Step 6: Evaluation/Review

Time: 7 minutes
Teaching Skill: Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

What is a formula?
What does changing the subject mean?
Change the subject of ( A = l times b ) to make ( b ) the subject.
From ( v = u + at ), make ( t ) the subject.
If ( l = 8 ) and ( b = 3 ), find ( A ).
Pupils’ Activity: Pupils answer the questions individually.
Learning Point: Pupils’ understanding of the topic is assessed.

Step 7: Conclusion

Time: 3 minutes
Teaching Skill: Summary
Teacher’s Activity: The teacher summarizes the lesson and highlights the importance of accuracy in changing the subject of a formula.
Pupils’ Activity: Pupils listen and ask final questions.
Learning Point: Pupils internalize the key ideas of the lesson.

Lesson Keywords

Formula – a rule showing the relationship between quantities.
Subject – the variable isolated in a formula.
Rearrangement – changing the order to isolate a variable.
Inverse Operation – opposite operation used to isolate variables.
Substitution – replacing variables with values.

Differentiation

Provide simpler formulae for slower learners while offering complex multi-step formulae to advanced learners; use peer support and guided practice for struggling pupils.

Note for teachers using this lesson plan

Encourage pupils to show every algebraic step clearly. Avoid skipping steps to prevent errors. Reinforce the use of inverse operations when isolating a variable.