Subtraction & Numbers 81-100 – Basic 1 Mathematics Lesson Note (Second Term)

Subject: Mathematics
Class: Primary 1
Topic: Subtraction & Numbers 81-100
Duration: 40 minutes

Learning Objectives

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

• Count numbers from 81 to 100
• Count backwards from 100
• Subtract two 1-digit numbers within 10
• Apply subtraction concepts in real situations

1. COUNTING SKILL: Numbers 81-90

Let’s Learn 81 to 90: 

81 – EIGHTY-ONE 

82 – EIGHTY-TWO 

83 – EIGHTY-THREE 

84 – EIGHTY-FOUR 

85 – EIGHTY-FIVE 

86 – EIGHTY-SIX 

87 – EIGHTY-SEVEN 

88 – EIGHTY-EIGHT 

89 – EIGHTY-NINE 

90 – NINETY

Exercise 1: Count from 81 to 90: 81, 82, 83, 84, 85, 86, 87, 88, 89, 90

Exercise 2: Fill in the missing numbers:

1. 81, 82, ___, 84, ___
2. 85, ___, 87, ___, 89
3. 83, 84, ___, 86, ___

2. COUNTING SKILL: Numbers 91-100

Let’s Learn 91 to 100: 

91 – NINETY-ONE 

92 – NINETY-TWO 

93 – NINETY-THREE 

94 – NINETY-FOUR 

95 – NINETY-FIVE 

96 – NINETY-SIX 

97 – NINETY-SEVEN 

98 – NINETY-EIGHT 

99 – NINETY-NINE 

100 – ONE HUNDRED

Exercise 3: Count from 91 to 100: 91, 92, 93, 94, 95, 96, 97, 98, 99, 100

Exercise 4: Complete these sequences:

1. 88, 89, 90, ___, ___, ___
2. 96, 97, ___, ___, 100
3. 78, 79, 80, ___, ___, ___

Exercise 5: Count from 1 to 100 by tens: 1-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, 81-90, 91-100

3. COUNTING BACKWARDS: 100 to 1

Counting Backwards from 100: 100, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90…

Exercise 6: Count backwards from 100 to 91: 100, 99, 98, 97, 96, 95, 94, 93, 92, 91

Exercise 7: Fill in backwards counting:

1. 100, 99, ___, 97, ___
2. 95, 94, ___, 92, ___
3. 88, 87, ___, 85, ___

Exercise 8: Count backwards from these numbers:

1. 87: ___, ___, ___, ___
2. 94: ___, ___, ___, ___
3. 100: ___, ___, ___, ___, ___

4. SUBTRACTION: Two 1-Digit Numbers Within 10

What is Subtraction? Subtraction means taking away numbers to find what is left. We use the – sign to subtract.

Simple Subtraction:

• 5 – 2 = 3
• 8 – 3 = 5
• 7 – 4 = 3
• 9 – 1 = 8

Exercise 9: Subtract these numbers:

1. 6 – 2 = ___
2. 8 – 5 = ___
3. 7 – 3 = ___
4. 9 – 4 = ___
5. 10 – 6 = ___

Exercise 10: Complete the subtraction:

1. 🍎🍎🍎🍎🍎🍎 – 🍎🍎 = ___
2. ⭐⭐⭐⭐⭐⭐⭐⭐ – ⭐⭐⭐ = ___
3. 🏀🏀🏀🏀🏀🏀🏀 – 🏀🏀🏀🏀 = ___

Exercise 11: Find what is left:

1. 9 – 2 = ___
2. 8 – 6 = ___
3. 10 – 3 = ___
4. 7 – 5 = ___

Exercise 12: Take away:

1. 10 – 0 = ___
2. 6 – 6 = ___
3. 8 – 1 = ___
4. 5 – 5 = ___

5. APPLICATION OF SUBTRACTION CONCEPTS

Real-Life Subtraction:

Story Problems:

• Tom had 7 apples. He ate 3 apples. How many are left? 7 – 3 = 4 apples
• Mary had 10 pencils. She gave away 4 pencils. How many are left? 10 – 4 = 6 pencils

Exercise 13: Solve these problems:

1. There were 8 birds in a tree. 3 flew away. How many are left? 8 – 3 = ___
2. I had 9 sweets. I ate 5 sweets. How many are left? 9 – 5 = ___
3. There were 6 books on the table. 2 were taken away. How many are left? 6 – 2 = ___

Exercise 14: Complete the story:

1. Sarah had ___ balloons. 2 balloons burst. She has 5 balloons left. ___ – 2 = 5
2. There were 10 cars in the park. ___ cars drove away. 7 cars are left. 10 – ___ = 7

Exercise 15: Draw and subtract:

1. Draw 7 circles. Cross out 2. How many are left? ___
2. Draw 9 stars. Cross out 4. How many are left? ___

Exercise 16: Match the subtraction to the answer:

• 8 – 3 → 2
• 6 – 4 → 5
• 7 – 2 → 6
• 9 – 3 → 5

Exercise 17: True or False:

1. 10 – 4 = 6 ___
2. 8 – 2 = 5 ___
3. 7 – 7 = 0 ___
4. 9 – 1 = 8 ___

Homework

1. Practice counting from 81 to 100 and back to 81
2. Practice subtraction problems within 10
3. Find subtraction situations at home (toys taken away, food eaten, etc.)
4. Write 3 subtraction word problems about your day
5. Count backwards from 100 to 90

Teacher: Use physical objects to demonstrate taking away for subtraction concepts