Addition (101–110) — Adding Numbers and Exploring Fact Families – Primary 1 Basic Science Lesson Note

COUNTING NUMBERS 51–100 (INCLUDING ORDERING, SKIP COUNTING, ADDITION AND SUBTRACTION PRACTICE)

Theme: Whole Numbers

Sub-theme: Number Sense

Class: Primary 1

Subject: Mathematics

Term: Second Term

Week: 4

Topic: Counting Numbers 51–100

Duration: 40 Minutes

Period: Single

Reference Materials:

• NERDC Mathematics Curriculum for Basic Education
• Primary 1 Mathematics Textbook
• Number Charts and Flash Cards

Performance Objectives:

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

1. Count numbers from 51 to 100 correctly.
2. Arrange numbers between 51 and 100 in ascending and descending order.
3. Perform skip counting in 2s, 5s, and 10s within 100.
4. Add and subtract numbers within 100.
5. Identify missing numbers in number patterns.

Instructional Materials:

• Number chart (1–100)
• Flash cards showing numbers 51–100
• Abacus or bottle tops for counting
• Charts showing skip counting in 2s, 5s, and 10s
• Whiteboard and markers

Content Development

Step 1: Introduction

Teacher revises numbers 1–50 from the previous week and asks:

• “Who can count from 1 to 50?”
• “What number comes after 50?”
  Pupils respond: “51!”

Teacher then explains that today they will learn to count, arrange, and use numbers from 51 to 100.

Step 2: Presentation

1. Counting Numbers 51–100

Counting means saying numbers in order — one after another.

Let’s count together:
51, 52, 53, 54, 55, 56, 57, 58, 59, 60,
61, 62, 63, 64, 65, 66, 67, 68, 69, 70,
71, 72, 73, 74, 75, 76, 77, 78, 79, 80,
81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
91, 92, 93, 94, 95, 96, 97, 98, 99, 100.

📊 Illustration:

[Insert Number Chart showing numbers 51–100 in a 10×5 grid]

1. Ordering Numbers (Ascending and Descending)

• Ascending order means arranging numbers from smallest to biggest.
  Example: 51, 52, 53, 54, 55
• Descending order means arranging numbers from biggest to smallest.
  Example: 55, 54, 53, 52, 51

🧮 Activity:
Write these numbers in ascending order:
67, 62, 65, 61, 63 → 61, 62, 63, 65, 67

1. Skip Counting

• By 2s: 52, 54, 56, 58, 60, 62, 64, 66, 68, 70
• By 5s: 55, 60, 65, 70, 75, 80, 85, 90, 95, 100
• By 10s: 60, 70, 80, 90, 100

📘 Illustration:

[Insert colorful skip-counting ladder diagram showing steps of +2, +5, +10 up to 100]

1. Simple Addition and Subtraction Practice

• 50 + 2 = 52
• 55 + 5 = 60
• 100 – 10 = 90
• 90 – 5 = 85

🧩 Illustration:

[Insert diagram showing 10 blocks being added and subtracted]

Step 3: Class Activities

Class Exercise 1:

Count and fill in the missing numbers:
a. 51, 52, ___, 54, ___, 56, ___, 58
b. 60, 65, 70, ___, ___, 85, ___, 95, 100
c. 100, 99, ___, 97, ___, 95, ___, 93

Class Exercise 2:

Solve these problems:

1. What is the number after 78?
2. What is the number before 64?
3. Count in 5s from 55 to 100.
4. 60 + 5 = ?
5. 85 – 10 = ?

Step 4: Board Summary

Step 5: Evaluation (5 MCQs)

1. What number comes after 59?
   A. 58 B. 60 C. 61 D. 62
2. Which of these numbers is the biggest?
   A. 77 B. 70 C. 75 D. 73
3. What comes next in this pattern: 60, 65, 70, ___
   A. 72 B. 75 C. 80 D. 85
4. Count by 10s: 70, ___, 90, ___
   A. 75, 95 B. 80, 100 C. 85, 90 D. 60, 80
5. What is 95 – 5?
   A. 85 B. 90 C. 100 D. 80

Answer Key: 1(B), 2(A), 3(B), 4(B), 5(B)