UNIQUE FRIENDS SCHOOLSSubject: Mathematics
Class: Basic 2
Topic: Open Sentence (Addition and Subtraction)
Duration: 40 Minutes
Learning Objectives
By the end of the lesson, pupils should be able to:
Explain what an open sentence is.
Find the missing number in addition sentences.
Find the missing number in subtraction sentences.
CONTENT :
5 + 3 = 8
9 – 4 = 5
WHAT IS AN OPEN SENTENCE
An open sentence is a number sentence that has a missing number.
The missing number can be shown with a box (□), a line (___), or a letter.
Example:
5 + ___ = 9
The sentence is open because one number is missing.
OPEN SENTENCE IN ADDITION
To find the missing number:
Ask yourself, “What number will make the sentence correct?”
Examples
4 + 3 = 7
Missing number is 3
2. ___ + 6 = 10
4 + 6 = 10
Missing number is 4
3. 8 + ___ = 12
8 + 4 = 12
Missing number is 4
4. ___ + 5 = 9
4 + 5 = 9
Missing number is 4
5. 3 + ___ = 11
3 + 8 = 11
Missing number is 8
OPEN SENTENCE IN SUBTRACTION
To find the missing number in subtraction:
Think about addition to help you.
Examples
9 – 4 = 5
Missing number is 4
2. ___ – 3 = 6
9 – 3 = 6
Missing number is 9
3. 15 – ___ = 10
15 – 5 = 10
Missing number is 5
4. ___ – 7 = 8
15 – 7 = 8
Missing number is 15
5. 14 – ___ = 9
14 – 5 = 9
Missing number is 5
CLASS ACTIVITY (GUIDED PRACTICE)
Solve together in class:
2. ___ + 7 = 12
3. 10 – ___ = 6
4. ___ – 4 = 5
5. 13 – ___ = 8
CLASS WORK
Fill in the missing numbers:
2. ___ + 9 = 14
3. 7 + ___ = 13
4. 11 – ___ = 7
5. ___ – 5 = 10
6. 16 – ___ = 9
8. ___ + 4 = 15
9. 18 – ___ = 12
HOMEWORK
2. ___ + 8 = 17
3. 12 – ___ = 5
4. ___ – 6 = 9
5. 20 – ___ = 13
6. 9 + ___ = 16
7. ___ – 8 = 7
8. 25 – ___ = 20
9. ___ + 3 = 11
10. 30 – ___ = 18