Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 1st Term
Week: 7
Age: 15 years
Duration: 45 minutes
Subject: General Mathematics
Curriculum Theme: General Mathematics
Previous Lesson: Indices: Laws and Exponential Equations.
Topic: LOGARITHM (II)
Subject Matter: Calculations involving multiplication and division using logarithm tables.

Specific Objectives

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

Cognitive Domain:

Recall the basic definition and laws of logarithms.
State the logarithm rules for multiplication and division.
Apply logarithm rules to simplify expressions involving multiplication and division.
Perform calculations involving multiplication and division of numbers using logarithm tables.

Affective Domain:

Appreciate the importance of logarithms in simplifying complex calculations.
Develop patience and accuracy when using logarithm tables.
Participate actively in class discussions and problem-solving.

Psychomotor Domain:

Accurately use logarithm and antilogarithm tables to find values.
Solve problems involving multiplication and division of numbers using logarithm tables.
Present solutions neatly and systematically.

Work cooperatively with peers to understand and solve logarithm problems.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum (Mathematics)
State Unified Scheme of Work (Mathematics)
New General Mathematics for Senior Secondary Schools 1

Instructional Materials

The teacher will teach this lesson with the aid of:

Logarithm table chart (flex banner)
Antilogarithm table chart (flex banner)
Logarithm table booklet

Rationale for the Lesson

Logarithms simplify complex arithmetic operations, making it easier to handle large numbers and intricate calculations. Understanding how to use logarithm tables for multiplication and division helps pupils solve real-world problems more efficiently and accurately.

Prerequisite/Previous Knowledge

Pupils have been introduced to the concept of logarithms, basic laws of logarithms, and how to read logarithm tables in the previous lesson.

Lesson Content/Board Summary

LOGARITHM (II): Calculations involving multiplication and division using logarithm tables.

Revision of Logarithm (I)

A logarithm is the power to which a base must be raised to produce a given number. For example, if 10² = 100, then log₁₀ 100 = 2.

Rules of Logarithm for Multiplication and Division

The following are the rules for logarithms involving multiplication and division:

log (a × b) = log a + log b
log (a ÷ b) = log a – log b

Steps for Calculation using Logarithm Tables

The following are the steps to calculate using logarithm tables:

Identify the numbers to be multiplied or divided.
Find the logarithm of each number using the logarithm table.
Apply the appropriate rule (add logs for multiplication, subtract logs for division).
Find the antilogarithm of the result to get the final answer.

Worked Examples

Example 1: Evaluate 23.45 × 8.76 using logarithm tables.

Solution:

   Number      Logarithm
   23.45       1.3701
   8.76        0.9425
   ------------------
   Add logs    2.3126  (for multiplication)
   Antilog of 2.3126 = 205.4

Therefore, 23.45 × 8.76 = 205.4 (approximately)

Example 2: Evaluate 456.7 ÷ 12.3 using logarithm tables.

Solution:

   Number      Logarithm
   456.7       2.6596
   12.3        1.0899
   ------------------
   Subtract logs 1.5697 (for division)
   Antilog of 1.5697 = 37.13

Therefore, 456.7 ÷ 12.3 = 37.13 (approximately)

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 reminds them of the previous lesson on logarithms, asking them to state one law of logarithm they remember.
Pupils’ Activity: Pupils respond to the greetings and state a law of logarithm, e.g., log (aⁿ) = n log a.
Learning Point: Pupils recall prior knowledge related to logarithms.

Step 2: Presentation of Topic

Time: 5 minutes
Teaching Skill: Explanation/Introduction
Teacher’s Activity: The teacher introduces the topic “LOGARITHM (II): Calculations involving multiplication and division using logarithm tables” and writes it on the board. The teacher then quickly reviews the rules for multiplication and division using logarithms.
Pupils’ Activity: Pupils listen attentively and write down the topic in their notebooks.
Learning Point: Pupils are introduced to the lesson’s specific focus.

Step 3: Explanation of Multiplication using Logarithms

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains in detail how to perform multiplication using logarithm tables, demonstrating with Example 1 from the board summary. The teacher guides pupils on how to find the logarithm of numbers and then add them, finally finding the antilogarithm.
Pupils’ Activity: Pupils observe the teacher’s demonstration, ask questions, and follow along with their logarithm tables.
Learning Point: Pupils understand the process of multiplication using logarithm tables.

Step 4: Explanation of Division using Logarithms

Time: 10 minutes
Teaching Skill: Demonstration/Explanation
Teacher’s Activity: The teacher explains how to perform division using logarithm tables, demonstrating with Example 2 from the board summary. The teacher guides pupils on how to find the logarithm of numbers and then subtract them, finally finding the antilogarithm.
Pupils’ Activity: Pupils observe the teacher’s demonstration, ask questions, and follow along with their logarithm tables.
Learning Point: Pupils understand the process of division using logarithm tables.

Step 5: Guided Practice

Time: 5 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher writes another simple multiplication or division problem on the board and guides pupils step-by-step through solving it, encouraging them to find the log and antilog values themselves.
Pupils’ Activity: Pupils attempt to solve the problem with the teacher’s guidance, using their logarithm tables.
Learning Point: Pupils apply the learned steps with immediate feedback.

Step 6: Further Practice/Problem Solving

Time: 5 minutes
Teaching Skill: Problem Solving
Teacher’s Activity: The teacher gives one more problem for pupils to solve independently or in pairs, circulating to provide assistance as needed.
Pupils’ Activity: Pupils work individually or in pairs to solve the given problem.
Learning Point: Pupils reinforce their understanding through independent practice.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

State the logarithm rule for multiplication.
State the logarithm rule for division.
Explain the steps involved in calculating 34.5 × 6.78 using logarithm tables.
Using logarithm tables, evaluate 25.6 × 3.14.

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/Assignment
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the rules for multiplication and division using logarithms and the importance of accuracy. The teacher then gives an assignment.
Assignment: Using logarithm tables, evaluate:
a) 78.9 × 0.543
b) 987.6 ÷ 45.1
Pupils’ Activity: Pupils listen to the summary and copy the assignment.
Learning Point: Pupils consolidate their learning and prepare for further practice.

Lesson Keywords

Logarithm – The power to which a base must be raised to produce a given number.
Antilogarithm – The number whose logarithm is a given number.
Characteristic – The integral part of a logarithm.
Mantissa – The decimal part of a logarithm.

Differentiation

For pupils who grasp the concept quickly, the teacher will provide more complex problems involving more than two numbers or a combination of multiplication and division. For struggling pupils, the teacher will provide additional one-on-one guidance, simplified examples, and step-by-step checklists for using the logarithm tables.

Note for teachers using this lesson plan

Ensure that all pupils have access to logarithm tables. Emphasize the importance of accuracy in reading the tables and performing arithmetic operations. Encourage pupils to practice regularly to improve their speed and precision.