Whole Numbers – Counting & Writing 1-20 Basic 1 Mathematics Lesson Note

Subject: Mathematics
Class: Primary 1
Topic: Whole Numbers – Counting & Writing 1-20
Duration: 35 minutes

Learning Objectives

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

• Count numbers from 11 to 20 correctly
• Count backwards from 20 to 1
• Write numbers 1 to 20 properly
• Sort and classify objects using numbers 1-20

1. COUNTING SKILL: Numbers 11-20

Let’s Count 11 to 20: 

11 – ELEVEN 

12 – TWELVE 

13 – THIRTEEN 

14 – FOURTEEN 

15 – FIFTEEN 

16 – SIXTEEN 

17 – SEVENTEEN 

18 – EIGHTEEN 

19 – NINETEEN 

20 – TWENTY

Exercise 1: Count from 11 to 20: 11, 12, 13, 14, 15, 16, 17, 18, 19, 20

Exercise 2: Fill in the missing numbers:

1. 11, 12, ___, 14, ___
2. 15, ___, 17, ___, 19
3. 12, 13, ___, 15, ___
4. 17, ___, 19, ___

Exercise 3: Complete the counting:

1. 10, 11, ___, ___, 14
2. 16, ___, ___, 19, ___
3. 13, 14, ___, ___, 17

2. REVERSE COUNTING: 20 to 1

Counting Backwards from 20 to 1: 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

Exercise 4: Count backwards from 20: 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1

Exercise 5: Fill in backwards counting:

1. 20, 19, ___, 17, ___
2. 15, 14, ___, 12, ___
3. 10, 9, ___, 7, ___

Exercise 6: Complete backwards from these numbers:

1. 18, 17, ___, ___, ___
2. 13, 12, ___, ___, ___
3. 8, 7, ___, ___, ___

3. WRITING SKILL: Numbers 1-20

How to Write Teen Numbers: 

11 – two ones side by side 

12 – one and two together 

13 – one and three together 

14 – one and four together 

15 – one and five together 

16 – one and six together 

17 – one and seven together 

18 – one and eight together 

19 – one and nine together 

20 – two and zero together

Exercise 7: Trace numbers 11-15: 11 11 11 11 12 12 12 12 13 13 13 13 14 14 14 14 15 15 15 15

Exercise 8: Trace numbers 16-20: 16 16 16 16 17 17 17 17 18 18 18 18 19 19 19 19 20 20 20 20

Exercise 9: Write numbers 1-10: 1 ___ 2 ___ 3 ___ 4 ___ 5 ___ 6 ___ 7 ___ 8 ___ 9 ___ 10 ___

Exercise 10: Write numbers 11-20: 11 ___ 12 ___ 13 ___ 14 ___ 15 ___ 16 ___ 17 ___ 18 ___ 19 ___ 20 ___

Exercise 11: Write the missing numbers:

1. 1, 2, 3, ___, 5, ___, 7, ___, 9, ___
2. 11, ___, 13, ___, 15, ___, 17, ___, 19, ___
3. 16, 17, ___, ___, 20

4. SORTING & CLASSIFICATION: Objects 1-20

Sorting by Numbers:

• Group objects by how many there are
• Put same numbers together
• Count carefully

Exercise 12: Count and write the number:

1. 🍎🍎🍎🍎🍎🍎🍎🍎🍎🍎🍎🍎 = _____
2. ⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐ = _____
3. 🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀🏀 = _____

Exercise 13: Sort these numbers into groups: Numbers: 5, 12, 3, 18, 7, 15, 2, 19, 9, 14

Numbers 1-10: _______________ Numbers 11-20: _______________

Exercise 14: Circle the larger number:

1. 8 or 15? ___
2. 12 or 6? ___
3. 19 or 9? ___
4. 4 or 14? ___

Exercise 15: Put these numbers in order (smallest to largest): Numbers: 16, 3, 11, 8, 20, 1, 15

Order: ___, ___, ___, ___, ___, ___, ___

Exercise 16: Group by tens: Numbers: 7, 13, 2, 18, 5, 11, 20, 4, 16, 9

1-10: _______________ 11-20: _______________

Exercise 17: Count objects and classify: (Teacher provides different groups of objects)

1. Group with 13 items: _____
2. Group with 8 items: _____
3. Group with 17 items: _____

Homework

1. Practice counting from 1 to 20 forward and backward
2. Write numbers 1-20 three times each
3. Count 15 objects at home and write the number
4. Find groups of objects at home and count them (1-20)
5. Sort 20 small objects into two groups: 1-10 and 11-20

Teacher: Use counting blocks, fingers, or real objects to make numbers concrete and visual