Class: Junior Secondary School 2 (JSS 2 / JS2)
Term: 3rd Term
Week: 6
Age: 13 years
Duration: 45 minutes
Subject: Mathematics
Curriculum Theme: Mathematics
Previous Lesson: Approximation Ii: Problems Using the Basic Arithmetic Operations Involving.
Topic: READY RECKONERS
Subject Matter: Ready Reckoners

Specific Objectives

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

Cognitive Domain:

Define what a ready reckoner is.
State at least two uses of ready reckoners.
Identify different types of ready reckoners.

Affective Domain:

Appreciate the importance of ready reckoners for quick calculations.
Show interest in using ready reckoners to solve mathematical problems.

Psychomotor Domain:

Use simple ready reckoners to perform calculations.
Solve practical problems involving the use of ready reckoners.

Collaborate with peers to understand and apply ready reckoner concepts.
Share examples of ready reckoners found in daily life.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Mathematics JSS 2.
State Unified Scheme of Work for Mathematics JSS 2.
New General Mathematics for Junior Secondary Schools, Book 2.
https://www.waeconline.org.ng/e-learning/Mathematics/MathsSS2.pdf
https://nigerianinfopedia.com.ng/mathematics-jss2-scheme-of-work/

Instructional Materials

The teacher will teach this lesson with the aid of:

A chart showing a simple multiplication table.
A chart showing a simple unit conversion table (e.g., Naira to a fixed foreign currency rate).
Textbooks and workbooks.

Rationale for the Lesson

This lesson helps pupils understand and use ready reckoners, which are useful tools for performing quick calculations in everyday situations and commercial transactions. It saves time and reduces errors in common mathematical problems.

Prerequisite/Previous Knowledge

Pupils have prior knowledge of basic arithmetic operations such as addition, subtraction, multiplication, and division.

Lesson Content/Board Summary

Ready Reckoners

Definition of Ready Reckoners

A ready reckoner is a table or book containing pre-calculated results for frequently recurring problems. It is designed to save time and effort in performing calculations.

Uses of Ready Reckoners

To perform quick calculations for common problems.
To save time in commercial transactions and business operations.
To check the accuracy of manual calculations.

Types of Ready Reckoners

Multiplication tables
Unit conversion tables (e.g., currency, length, weight)
Simple interest tables
Discount tables
Tax tables
Wage tables

How to Use a Ready Reckoner (Worked Examples)

Ready reckoners are used by locating the required value in the table and reading off the corresponding result.

Example 1: Using a Multiplication Ready Reckoner

A ready reckoner (multiplication table) shows that 1 item costs N25. Use it to find the cost of 7 such items.

Step 1: Locate the unit cost (N25) and the quantity (7 items).
Step 2: Multiply the unit cost by the quantity: 7 × N25.
Step 3: Read the result from the table or calculate: N175.

Therefore, 7 items will cost N175.

Example 2: Using a Conversion Ready Reckoner

A ready reckoner shows that 1 meter (m) is equal to 100 centimeters (cm). How many centimeters are in 4.5 meters?

Step 1: Identify the conversion rate from the ready reckoner: 1 m = 100 cm.
Step 2: Multiply the given length in meters by the conversion rate: 4.5 m × 100 cm/m.
Step 3: Calculate the result: 450 cm.

Therefore, 4.5 meters is equal to 450 centimeters.

NOTE: When converting from smaller units to larger units divide, but when converting from larger units to smaller units multiply.

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 asks pupils how they quickly calculate the total cost of multiple items at a market or convert units without a calculator. The teacher then introduces the topic of “Ready Reckoners” as a tool for such quick calculations.
Pupils’ Activity: Pupils respond by mentioning mental calculations or using basic arithmetic. They listen attentively to the introduction.
Learning Point: Pupils are introduced to the concept of ready reckoners and their purpose.

Step 2: Explanation of Ready Reckoners

Time: 7 minutes
Teaching Skill: Explanation/Definition
Teacher’s Activity: The teacher defines a ready reckoner, explaining that it is a table of pre-calculated results for common problems. The teacher also explains why they are used (to save time and effort).
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the definition and purpose of ready reckoners.

Step 3: Discussing Uses and Types

Time: 8 minutes
Teaching Skill: Discussion/Categorization
Teacher’s Activity: The teacher leads a discussion on various uses of ready reckoners in daily life and business. The teacher then lists and explains different types of ready reckoners, such as multiplication tables, conversion tables, and interest tables, using the prepared charts.
Pupils’ Activity: Pupils contribute ideas on uses and identify different types of ready reckoners from the charts and their experiences.
Learning Point: Pupils identify practical uses and different categories of ready reckoners.

Step 4: Demonstration of Using a Ready Reckoner

Time: 10 minutes
Teaching Skill: Demonstration/Modeling
Teacher’s Activity: The teacher demonstrates how to use a simple ready reckoner with the worked examples on the board. The teacher guides pupils through each step of finding information and performing calculations.
Pupils’ Activity: Pupils observe carefully, ask questions, and follow the steps demonstrated by the teacher.
Learning Point: Pupils learn the practical application of ready reckoners through demonstrated examples.

Step 5: Guided Practice

Time: 7 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher provides additional simple problems and guides pupils to use the ready reckoners (charts or mental tables) to find solutions. The teacher offers support and corrects errors.
Pupils’ Activity: Pupils work on the problems, applying the steps demonstrated earlier, and seek assistance when needed.
Learning Point: Pupils gain confidence in using ready reckoners with teacher guidance.

Step 6: Problem Solving

Time: 5 minutes
Teaching Skill: Problem-Solving
Teacher’s Activity: The teacher gives pupils independent problems to solve, encouraging them to apply their understanding of ready reckoners. The teacher monitors their work.
Pupils’ Activity: Pupils solve the problems independently, demonstrating their ability to use ready reckoners.
Learning Point: Pupils apply their knowledge to solve problems independently.

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 a ready reckoner?
State two uses of ready reckoners.
Mention two types of ready reckoners you know.
If a ready reckoner shows that 1 kilogram of sugar costs N1200, how much will 3 kilograms cost?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 3 minutes
Teaching Skill: Summarization/Consolidation
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the definition, uses, and types of ready reckoners. The teacher then assigns homework related to using simple ready reckoners.
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their understanding of ready reckoners.

Lesson Keywords

Ready Reckoner – A table or book containing pre-calculated results for common problems.
Calculation – The process of determining an answer or result using mathematical operations.
Table – An arrangement of data in rows and columns.
Conversion – The process of changing one unit or value to another.
Interest – Money paid regularly at a particular rate for the use of money lent or for delaying the repayment of a debt.

Differentiation

For pupils who grasp the concept quickly, the teacher can provide more complex problems involving multi-step calculations or different types of ready reckoners. For those who need more support, the teacher will provide simpler ready reckoners and work through additional examples step-by-step, ensuring individual attention and peer tutoring where appropriate.

Note for teachers using this lesson plan

Teachers should ensure that clear and legible charts of simple ready reckoners are available for demonstration. Encourage pupils to create their own simple ready reckoners for everyday tasks, such as calculating costs for different quantities of items. Emphasize the practical benefits of using these tools for efficiency and accuracy in calculations.