Open Sentences : Addition, Subtraction, Multiplication and Division
LESSON PLAN ON OPEN SENTENCES INVOLVING ADDITION, SUBTRACTION, MULTIPLICATION, AND DIVISION
Subject: Mathematics
Class: Basic Four / Primary 4
Term: Second Term
Week: 10
Age: 8-9 years
Topic: Open Sentences Involving Addition, Subtraction, Multiplication, and Division
Sub-topic: Understanding and Solving Open Sentences
Duration: 40 Minutes
Behavioural Objectives
By the end of the lesson, pupils should be able to:
- Illustrate and explain the meaning of an open sentence.
- Predict and solve for missing numbers in open sentences.
- Differentiate between true and false mathematical statements.
- Solve equations involving addition, subtraction, multiplication, and division.
- Apply the concept to solve real-life problems and quantitative reasoning questions.
Keywords
- Open Sentence: A math equation with a missing number.
- Equation: A statement that shows equality between two expressions.
- Unknown: The missing value in an equation.
- Operation: Addition, subtraction, multiplication, or division.
Set Induction
The teacher shows a flashcard with a question such as 5 + __ = 12 and asks, “What number should we add to 5 to make 12?” Pupils are encouraged to guess the answer. This activity creates curiosity and introduces the concept of open sentences.
Entry Behaviour
Pupils are familiar with basic operations: addition, subtraction, multiplication, and division.
Learning Resources and Materials
- Flashcards with open sentences.
- Chalkboard/Whiteboard and markers.
- Counters or small objects for demonstration.
- Worksheets for practice.
Building Background/Connection to Prior Knowledge
The teacher reminds pupils of their knowledge of addition, subtraction, multiplication, and division. For example, the teacher writes 7 + 5 = 12 and asks, “Is this true?” Pupils respond, reinforcing the concept of equality.
Embedded Core Skills
- Critical Thinking: Solving for unknowns in equations.
- Collaboration: Working in groups to solve problems.
- Problem-Solving: Applying mathematical operations to find missing values.
- Personal Development: Building confidence in solving equations.
Learning Materials
- Lagos State Scheme of Work.
- Flashcards with equations.
- Practice worksheets.
Reference Books
- Lagos State Scheme of Work for Primary Schools.
- Basic Mathematics Textbook for Primary 4.
Instructional Materials
- Flashcards.
- Counters for visual representation.
- Board and markers.
Content
Definition and Explanation
- Open Sentence:
An open sentence is a math equation that contains a missing number or value, often represented by a box or symbol, such as__. - Mathematical Operations:
Open sentences can involve addition, subtraction, multiplication, or division. - Equality:
Open sentences include an equality sign=and require solving for the unknown to make the equation true. - Difference from Closed Sentences:
- Closed sentences have no missing values (e.g.,
4 + 5 = 9). - Open sentences include an unknown (e.g.,
4 + __ = 9).
- Closed sentences have no missing values (e.g.,
- Steps to Solve Open Sentences:
- Identify the operation (e.g., addition, subtraction).
- Reverse the operation to solve for the unknown.
Examples
- Addition:
7 + __ = 15→__ = 15 - 7 = 8. - Subtraction:
__ - 9 = 4→__ = 4 + 9 = 13. - Multiplication:
6 × __ = 36→__ = 36 ÷ 6 = 6. - Division:
40 ÷ __ = 8→__ = 40 ÷ 8 = 5. - Word Problem:
- A boy has 12 mangoes. If he gives some away and has 7 left, how many did he give away?
- Open sentence:
12 - __ = 7. Solve:__ = 12 - 7 = 5.
Class Activity Discussion
Frequently Asked Questions (FAQs):
- What is an open sentence?
Answer: A math equation with a missing number or unknown value. - What does
__in a sentence mean?
Answer: It represents the unknown value we need to find. - How do you solve
8 + __ = 14?
Answer: Subtract 8 from 14 to find__ = 6. - Can open sentences be false?
Answer: No, they are solved to make the equation true. - How is subtraction used in open sentences?
Answer: By reversing addition to find the missing value. - What is the opposite of addition?
Answer: Subtraction. - Solve:
__ × 4 = 20.
Answer:__ = 20 ÷ 4 = 5. - Why is an equation called “open”?
Answer: Because part of it is missing. - What is the solution to
10 ÷ __ = 2?
Answer:__ = 10 ÷ 2 = 5. - Are open sentences always math problems?
Answer: Yes, they involve finding unknown values.
Evaluation
Fill-in-the-Blank Questions
- 6 + __ = 14.
a) 6 b) 8 c) 10 d) 7 - __ – 5 = 15.
a) 20 b) 25 c) 15 d) 10 - 3 × __ = 27.
a) 6 b) 9 c) 7 d) 8 - 48 ÷ __ = 12.
a) 6 b) 4 c) 3 d) 8 - 10 + __ = 22.
a) 12 b) 14 c) 10 d) 20
Short Answer Questions
- Solve
8 × __ = 64. - What is the missing value in
30 ÷ __ = 6? - If
5 + __ = 13, find the unknown. - Solve
__ - 9 = 11. - Write an open sentence for “Divide 72 by a number to get 9.”
Presentation Steps
- Revision: The teacher revises the previous topic, “Closed Sentences in Math.”
- Introduction: The teacher introduces open sentences with simple examples on the board.
- Guided Practice: Pupils solve equations with teacher guidance.
- Independent Practice: Pupils work on their own or in groups using flashcards and worksheets.
- Corrections: The teacher reviews and corrects answers with the pupils.
Teacher’s Activities
- Explains the meaning and examples of open sentences.
- Demonstrates how to solve equations step-by-step.
- Provides practice questions and guides pupils.
Learners’ Activities
- Participate in class discussions.
- Solve practice questions on open sentences.
- Share answers and explain their methods.
Conclusion
The teacher reviews the topic by solving one last example on the board and explains the importance of understanding open sentences. Feedback is provided to pupils.