Math Facts & Numbers 71-80 – Basic 1 Mathematics Lesson Note (Second Term)

Subject: Mathematics
Class: Primary 1
Topic: Math Facts & Numbers 71-80
Duration: 40 minutes

Learning Objectives

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

• Count numbers from 71 to 80 and 1 to 80
• Add two 1-digit numbers with sum not more than 20
• Add three 1-digit numbers with sum not more than 20
• Understand doubles and near doubles
• Count forward in 2s and 3s

1. COUNTING SKILL: Numbers 71-80

Let’s Learn 71 to 80: 

71 – SEVENTY-ONE 

72 – SEVENTY-TWO 

73 – SEVENTY-THREE 

74 – SEVENTY-FOUR 

75 – SEVENTY-FIVE 

76 – SEVENTY-SIX 

77 – SEVENTY-SEVEN 

78 – SEVENTY-EIGHT 

79 – SEVENTY-NINE 

80 – EIGHTY

Exercise 1: Count from 71 to 80: 71, 72, 73, 74, 75, 76, 77, 78, 79, 80

Exercise 2: Fill in the missing numbers:

1. 71, 72, ___, 74, ___
2. 75, ___, 77, ___, 79
3. 73, 74, ___, 76, ___

Exercise 3: Count from 1 to 80 by tens: 1-10, 11-20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80

Exercise 4: Complete these sequences:

1. 68, 69, 70, ___, ___, ___
2. 76, 77, ___, ___, 80

2. ADDITION: Two 1-Digit Numbers (Sum ≤ 20)

Adding Bigger Numbers: When we add two numbers, we get a sum.

• 7 + 8 = 15
• 9 + 6 = 15
• 5 + 9 = 14
• 8 + 7 = 15

Exercise 5: Add these numbers:

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

Exercise 6: Complete the addition:

1. 🍎🍎🍎🍎🍎🍎🍎 + 🍎🍎🍎🍎 = ___
2. ⭐⭐⭐⭐⭐⭐⭐⭐ + ⭐⭐⭐⭐⭐ = ___

Exercise 7: Find the sum:

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

3. ADDITION: Three 1-Digit Numbers (Sum ≤ 20)

Adding Three Numbers: Add the first two numbers, then add the third number.

• 3 + 4 + 2 = 7 + 2 = 9
• 2 + 5 + 3 = 7 + 3 = 10
• 4 + 3 + 5 = 7 + 5 = 12

Exercise 8: Add three numbers:

1. 2 + 3 + 4 = ___
2. 1 + 5 + 2 = ___
3. 3 + 2 + 6 = ___
4. 4 + 1 + 3 = ___
5. 2 + 4 + 5 = ___

Exercise 9: Find the total:

1. 🏀🏀 + 🏀🏀🏀 + 🏀🏀🏀🏀 = ___
2. 📚📚📚 + 📚📚 + 📚📚📚📚 = ___

Exercise 10: Complete:

1. 3 + 3 + 4 = ___
2. 2 + 5 + 4 = ___
3. 4 + 2 + 7 = ___
4. 1 + 6 + 3 = ___

4. Doubles and near doubles

Doubles (Same Numbers):

• 6 + 6 = 12
• 7 + 7 = 14
• 8 + 8 = 16
• 9 + 9 = 18

Near Doubles (Almost the Same):

• 6 + 7 = 13 (6 + 6 + 1)
• 7 + 8 = 15 (7 + 7 + 1)
• 8 + 9 = 17 (8 + 8 + 1)

Exercise 11: Complete the doubles:

1. 6 + 6 = ___
2. 7 + 7 = ___
3. 8 + 8 = ___
4. 9 + 9 = ___

Exercise 12: Complete the near doubles:

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

Exercise 13: Circle doubles or near doubles:

1. 4 + 4 (Doubles/Near Doubles)
2. 5 + 6 (Doubles/Near Doubles)
3. 7 + 7 (Doubles/Near Doubles)
4. 8 + 9 (Doubles/Near Doubles)

5. COUNT FORWARD IN 2s AND 3s

Counting in 2s (Skip Counting by 2): 2, 4, 6, 8, 10, 12, 14, 16, 18, 20

Exercise 14: Count in 2s:

1. 2, 4, ___, 8, ___
2. 10, 12, ___, 16, ___
3. 6, 8, ___, 12, ___

Exercise 15: Continue counting in 2s:

1. 2, 4, 6, ___, ___, ___
2. 14, 16, 18, ___, ___

Counting in 3s (Skip Counting by 3): 3, 6, 9, 12, 15, 18, 21

Exercise 16: Count in 3s:

1. 3, 6, ___, 12, ___
2. 9, 12, ___, 18, ___

Exercise 17: Continue counting in 3s:

1. 3, 6, 9, ___, ___, ___
2. 12, 15, 18, ___

Exercise 18: Fill in the pattern:

1. Count by 2s: 2, ___, 6, ___, 10
2. Count by 3s: 3, ___, 9, ___, 15

Exercise 19: Which pattern?

1. 2, 4, 6, 8… (counting by ___)
2. 3, 6, 9, 12… (counting by ___)

Homework

1. Practice counting from 71 to 80 and 1 to 80
2. Practice addition problems with sums up to 20
3. Find doubles around your house (2 hands = 10 fingers, etc.)
4. Practice counting by 2s from 2 to 20
5. Practice counting by 3s from 3 to 21

Teacher: Use counting objects, number lines, and skip counting charts to demonstrate patterns