Class: Primary 3
Term: 2nd Term
Week: 3
Age: 8 years
Duration: 45 minutes
Subject: Mathematics
Curriculum Theme: Numbers
Previous Lesson: Division, Factors of Whole Numbers Not.
Topic: Division
Subject Matter: Find the missing factor in a given numbers

Specific Objectives

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

Cognitive Domain:

Define what a factor is.
Identify factors of given numbers using multiplication facts.
Find the missing factor in simple multiplication or division sentences.

Affective Domain:

Appreciate the relationship between multiplication and division.
Show interest in solving problems involving factors.

Psychomotor Domain:

Correctly write down factors of given numbers.
Accurately determine missing factors in number sentences.

Participate actively in group activities to solve factor problems.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Primary 3 Mathematics
State Unified Scheme of Work
New Oxford Primary Mathematics Book 3
Relevant charts and flashcards

Instructional Materials

The teacher will teach this lesson with the aid of:

Multiplication table chart
Rectangular array charts/diagrams
Counters or small objects
Flashcards with multiplication and division problems
Whiteboard and markers/chalk

Rationale for the Lesson

This lesson helps pupils to understand the inverse relationship between multiplication and division. It enables them to find unknown numbers in simple multiplication and division problems, which is important for developing stronger number sense and problem-solving skills in everyday life.

Prerequisite/Previous Knowledge

Pupils are expected to have prior knowledge of basic multiplication facts and simple division concepts.

Lesson Content/Board Summary

Division

Finding Missing Factors

A factor is a number that divides another number exactly, without leaving a remainder. Factors are also the numbers we multiply together to get another number (the product).

Using Rectangular Patterns to Find Factors

We can use rectangular patterns (arrays) to see the factors of a number. The number of rows and columns in a rectangle formed by a given total are its factors.

Example: Factors of 6

If we have 6 items, we can arrange them as:
- 1 row of 6 items (1 x 6 = 6)
- 6 rows of 1 item (6 x 1 = 6)
- 2 rows of 3 items (2 x 3 = 6)
- 3 rows of 2 items (3 x 2 = 6)
The factors of 6 are 1, 2, 3, and 6.

Finding Missing Factors in Number Sentences

To find a missing factor in a multiplication sentence, we use division. To find a missing factor in a division sentence, we can use multiplication or division.

Formula: Missing Factor = Product ÷ Known Factor

Worked Example 1: Finding the missing factor in multiplication

Find the missing factor: _ x 4 = 20

Step 1: Understand the problem. We need to find a number that, when multiplied by 4, gives 20.

Step 2: Use division. Divide the product (20) by the known factor (4).

Step 3: Calculate: 20 ÷ 4 = 5.

Step 4: Write the answer. The missing factor is 5. So, 5 x 4 = 20.

Worked Example 2: Finding the missing factor in division

Find the missing factor: 30 ÷ _ = 5

Step 1: Understand the problem. We need to find a number that divides 30 to give 5.

Step 2: Think of multiplication. What number multiplied by 5 gives 30? (5 x ? = 30)

Step 3: Calculate: 5 x 6 = 30.

Step 4: Write the answer. The missing factor is 6. So, 30 ÷ 6 = 5.

More Practice Numbers to find factors: 5, 6, 10, 12, 15, 18, 20, 24, 25, 30, 36

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Division: Finding Missing Factors

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and reviews previous knowledge by asking multiplication questions like, “What is 3 x 5?” and “What is 4 x 6?”.
Pupils’ Activity: Pupils respond to the multiplication questions.
Learning Point: Pupils recall basic multiplication facts relevant to the lesson.

Step 2: Introduction to Factors using Rectangular Patterns

Time: 10 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains what factors are and uses a chart or counters to demonstrate how to find factors of a number (e.g., 6) using rectangular arrays. The teacher shows arrangements like 1×6 and 2×3.
Pupils’ Activity: Pupils observe the demonstration and listen to the explanation.
Learning Point: Pupils understand the concept of factors and how to visualize them using arrays.

Step 3: Identifying Factors of Given Numbers

Time: 7 minutes
Teaching Skill: Guided Practice
Teacher’s Activity: The teacher writes numbers like 10 and 12 on the board and guides pupils to identify their factors using multiplication facts they already know. For example, for 10, “What two numbers multiply to give 10?”
Pupils’ Activity: Pupils actively participate by suggesting pairs of numbers that multiply to give the target number.
Learning Point: Pupils practice finding factors of different numbers.

Step 4: Introduction to Missing Factors

Time: 5 minutes
Teaching Skill: Explanation
Teacher’s Activity: The teacher introduces the concept of a “missing factor” using simple number sentences like “_ x 3 = 12” and “15 ÷ _ = 3”. The teacher explains that finding the missing factor helps us solve problems.
Pupils’ Activity: Pupils listen and try to guess the missing numbers.
Learning Point: Pupils understand what a missing factor problem looks like.

Step 5: Solving Missing Factor Problems

Time: 8 minutes
Teaching Skill: Demonstration/Problem-solving
Teacher’s Activity: The teacher demonstrates how to solve missing factor problems step-by-step using the examples from the board summary, such as “_ x 4 = 20” and “30 ÷ _ = 5”. The teacher emphasizes using division to find the missing factor in multiplication.
Pupils’ Activity: Pupils pay attention to the steps and ask questions for clarification.
Learning Point: Pupils learn the procedure for finding missing factors.

Step 6: Group Activity/Practice

Time: 5 minutes
Teaching Skill: Collaborative Learning
Teacher’s Activity: The teacher divides pupils into small groups and gives each group flashcards with missing factor problems. The teacher moves around to assist groups.
Pupils’ Activity: Pupils work collaboratively in their groups to solve the missing factor problems.
Learning Point: Pupils reinforce their understanding through peer interaction and 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:

What is a factor?
List the factors of 15.
Find the missing factor: _ x 5 = 25.
Find the missing factor: 24 ÷ _ = 4.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 3 minutes
Teaching Skill: Wrap-up
Teacher’s Activity: The teacher summarizes the lesson by reiterating the importance of factors in multiplication and division. The teacher assigns homework for pupils to practice finding factors and missing factors.
Pupils’ Activity: Pupils listen to the summary and copy down the homework.
Learning Point: Pupils consolidate their learning and prepare for independent practice.

Home Task: Solve three new exercises on Division. Show each step and check each answer.

Lesson Keywords

Factor – A number that divides another number exactly without a remainder.
Division – The process of splitting a number into equal parts.
Multiplication – The process of repeatedly adding a number to itself.
Missing Factor – An unknown number in a multiplication or division problem that needs to be found.
Rectangular Pattern – An arrangement of objects in rows and columns.

Differentiation

For pupils who are struggling, the teacher will provide extra support by using more physical manipulatives (counters) and simpler numbers. Advanced learners will be given more challenging problems or asked to create their own missing factor problems for others to solve.

Note for teachers using this lesson plan

Ensure pupils have a strong grasp of basic multiplication facts as this is fundamental to understanding factors and finding missing factors. Encourage the use of various strategies, including drawing arrays and using multiplication tables, to help pupils visualize and solve problems. Provide ample opportunities for practice both individually and in groups.