Addition and Subtraction (Two 2-digits numbers with and without renaming or exchanging) Mathematics Primary 2 First Term Lesson Notes Week 9

Subject: Mathematics

Class: Primary 2

Term: First Term

Week: 9

Topic: Addition and Subtraction (Two 2-Digit Numbers with and without Renaming or Exchanging)

Duration: 30 minutes

Previous Knowledge: Students have a basic understanding of addition and subtraction of 1-digit numbers.

Behavioral Objectives:

1. To introduce students to adding two 2-digit numbers without renaming.
2. To teach students how to add two 2-digit numbers with renaming when needed.
3. To guide students in subtracting two 2-digit numbers without borrowing.
4. To demonstrate subtraction with borrowing for 2-digit numbers.
5. To enhance students’ problem-solving skills in mathematics.

Embedded Core Skills:

• Mathematical operations (addition and subtraction)
• Problem-solving and critical thinking
• Number sense

Learning Materials:

• Number cards with 2-digit numbers
• A whiteboard and markers
• Visual aids for demonstration

Content:

• Introduction to adding and subtracting 2-digit numbers.
• Presentation of addition without renaming.
• Introduction to addition with renaming.
• Practical exercises for addition.
• Presentation of subtraction without borrowing.
• Introduction to subtraction with borrowing.
• Practical exercises for subtraction.

Addition (Without Renaming):

1. When we add two 2-digit numbers without renaming, it means we don’t need to carry or exchange any numbers.

   Example: 23 + 47

   • First, add the ones place: 3 + 7 = 10 (This is a 2-digit number, so write down 0 in the ones place and carry over 1 to the tens place).
   • Then, add the tens place: 2 (from 23) + 4 (from 47) + 1 (carried over) = 7.
   • So, 23 + 47 = 70.

Addition (With Renaming): 2. Sometimes, when we add two 2-digit numbers, we have to rename or exchange numbers to add them correctly.

Example: 56 + 48

• First, add the ones place: 6 + 8 = 14. Write down 4 in the ones place and carry over 1 to the tens place.
• Then, add the tens place: 5 (from 56) + 4 (from 48) + 1 (carried over) = 10.
• So, 56 + 48 = 104.

Subtraction (Without Borrowing): 3. When we subtract two 2-digit numbers without borrowing, it means we don’t need to take away from the tens place.

Example: 75 – 32

• First, subtract the ones place: 5 – 2 = 3.
• Then, subtract the tens place: 7 – 3 = 4.
• So, 75 – 32 = 43.

Subtraction (With Borrowing): 4. Sometimes, when we subtract two 2-digit numbers, we need to borrow or take away from the tens place.

Example: 86 – 49

• First, subtract the ones place: 6 – 9. We can’t do this, so we need to borrow from the tens place. Make the 8 into 7 and add 10 to the ones place.
• Now, subtract the ones place: 16 – 9 = 7.
• Then, subtract the tens place: 7 – 4 = 3.
• So, 86 – 49 = 37.

These examples show how we can add and subtract 2-digit numbers, both with and without renaming or exchanging. It’s like solving puzzles to find the right answer

Addition (Without Renaming):

1. 23 + 45 = 68
   • Ones: 3 + 5 = 8
   • Tens: 2 + 4 = 6
2. 37 + 28 = 65
   • Ones: 7 + 8 = 15 (Write down 5, carry over 1)
   • Tens: 3 + 2 + 1 (carried over) = 6
3. 49 + 16 = 65
   • Ones: 9 + 6 = 15 (Write down 5, carry over 1)
   • Tens: 4 + 1 (carried over) = 5

Addition (With Renaming): 4. 57 + 49 = 106

• Ones: 7 + 9 = 16 (Write down 6, carry over 1)
• Tens: 5 + 4 + 1 (carried over) = 10

5. 68 + 78 = 146
   • Ones: 8 + 8 = 16 (Write down 6, carry over 1)
   • Tens: 6 + 7 + 1 (carried over) = 14

Subtraction (Without Borrowing): 6. 82 – 36 = 46

• Ones: 2 – 6 (Can’t do it, so we don’t need to borrow)
• Tens: 8 – 3 = 5

7. 75 – 23 = 52
   • Ones: 5 – 3 = 2
   • Tens: 7 – 2 = 5

Subtraction (With Borrowing): 8. 74 – 58 = 16

• Ones: 4 – 8 (Can’t do it, so we need to borrow from tens)
• Tens: 6 – 5 = 1

9. 96 – 47 = 49
   • Ones: 6 – 7 (Can’t do it, so we need to borrow from tens)
   • Tens: 9 – 4 = 5
10. 73 – 29 = 44
    • Ones: 3 – 9 (Can’t do it, so we need to borrow from tens)
    • Tens: 6 – 2 = 4

These worked examples demonstrate how to add and subtract 2-digit numbers with and without renaming (in the case of addition) and with and without borrowing (in the case of subtraction). It’s important to understand when to use these techniques for different math problems

Presentation of Content:

• Step 1: Start by explaining the importance of adding and subtracting numbers in our daily lives.
• Step 2: Demonstrate addition of 2-digit numbers without renaming using visual aids and number cards.
• Step 3: Show students how to add with renaming when the sum is more than 9.
• Step 4: Provide practical exercises for students to practice addition.
• Step 5: Introduce subtraction without borrowing and demonstrate how to subtract 2-digit numbers.
• Step 6: Explain subtraction with borrowing when the top number is smaller than the bottom number.
• Step 7: Provide practical exercises for subtraction to reinforce learning.
• Addition (Without Renaming):
  1. 23 + 45 = ______ a) 58 b) 72 c) 68 d) 53
  2. 37 + 28 = ______ a) 47 b) 73 c) 53 d) 65
  3. 49 + 16 = ______ a) 59 b) 65 c) 31 d) 81

  Addition (With Renaming): 4. 57 + 49 = ______ a) 106 b) 78 c) 64 d) 96

  5. 68 + 78 = ______ a) 155 b) 146 c) 127 d) 135

  Subtraction (Without Borrowing): 6. 82 – 36 = ______ a) 48 b) 46 c) 28 d) 52

  7. 75 – 23 = ______ a) 23 b) 63 c) 52 d) 32

  Subtraction (With Borrowing): 8. 74 – 58 = ______ a) 15 b) 46 c) 16 d) 27

  9. 96 – 47 = ______ a) 41 b) 65 c) 57 d) 49
  10. 73 – 29 = ______ a) 44 b) 72 c) 13 d) 53

  These questions cover different scenarios of addition and subtraction, both with and without renaming or exchanging for 2-digit numbers

Teacher’s Activities:

• Explain the concept of adding and subtracting 2-digit numbers.
• Use visual aids and number cards to make learning interactive.
• Facilitate hands-on exercises and provide guidance.

Learners’ Activities:

• Listen and understand the concepts of addition and subtraction.
• Participate actively in solving mathematical problems.
• Practice Questions on and subtraction with provided materials.

Evaluation:

• Assess students’ ability to add and subtract 2-digit numbers, both with and without renaming or exchanging.
• Encourage students to solve practical problems using the newly acquired skills.
• Provide feedback and guidance as needed to improve their understanding.

More Questions

Addition (Without Renaming):

1. 35 + 27 = _____ a) 52 b) 63 c) 72
2. 48 + 39 = _____ a) 78 b) 87 c) 68
3. 56 + 14 = _____ a) 71 b) 60 c) 70

Addition (With Renaming): 4. 68 + 49 = _____ a) 105 b) 117 c) 117

5. 79 + 48 = _____ a) 135 b) 125 c) 127

Subtraction (Without Borrowing): 6. 76 – 42 = _____ a) 34 b) 56 c) 18

7. 58 – 29 = _____ a) 39 b) 25 c) 79

Subtraction (With Borrowing): 8. 84 – 57 = _____ a) 27 b) 67 c) 81

9. 93 – 49 = _____ a) 44 b) 64 c) 43
10. 75 – 38 = _____ a) 32 b) 43 c) 37

These questions cover different scenarios of addition and subtraction, both with and without renaming or exchanging for 2-digit numbers, and provide three options for each question

This lesson plan aims to help Primary 2 students grasp the concepts of addition and subtraction with 2-digit numbers, both with and without renaming or exchanging, and encourages active participation and hands-on learning for better understanding.