Mathematics - Primary 4 - Open Sentences

Open Sentences

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Term: 2nd Term

Week: 9

Class: Primary 4
Age: 9 years
Duration: 40 minutes of 5 periods
Date:
Subject: Mathematics
Topic: Open Sentences

SPECIFIC OBJECTIVES:

At the end of the lesson, pupils should be able to:

  1. ) Illustrate and explain the term open sentence.
  2. ) Predict the missing numbers in an open sentence.
  3. ) Write and solve equations based on open sentences.
  4. ) Solve quantitative reasoning problems involving open sentences.

INSTRUCTIONAL TECHNIQUES: Explanation, class discussion, hands-on activities, problem-solving.
INSTRUCTIONAL MATERIALS: Flashcards, board, worksheets, story prompts.

INSTRUCTIONAL PROCEDURES

PERIOD 1 and 2:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1 – INTRODUCTION

Introduces the concept of an open sentence in mathematics. Explains that an open sentence contains a missing number or variable.

Pupils listen and engage in a discussion about open sentences.

STEP 2 – EXPLANATION

Provides examples of open sentences:

  

Example 1: x + 5 = 10. The pupil needs to find what x equals.

    

Example 2: 3 × x = 15. The pupil needs to find x.

Pupils practice identifying the open sentence and the missing number.

  

STEP 3 – DEMONSTRATION

Solves open sentences with different types of variables on the board. Example: x + 7 = 12, solve for x.

Pupils solve similar problems, starting with simple equations.

STEP 4 – NOTE TAKING

Pupils take notes on how to solve open sentences, and the importance of identifying the variable.

Pupils write down steps for solving open sentences in their notebooks.

NOTE:

  • An open sentence has a variable (like x or y) that needs to be solved.
  • Example: x + 3 = 8 → x = 8 - 3 → x = 5.

EVALUATION:

  1. Solve for x: x + 4 = 10.
  2. Solve for y: 5 × y = 25.

CLASSWORK:

  1. Solve: x + 6 = 14.
  2. Solve: 7 × y = 28.

ASSIGNMENT:

  1. Solve: x + 2 = 10.
  2. Solve: 9 × y = 45.

PERIOD 3 and 4:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1 – INTRODUCTION

Recaps open sentences and introduces story problems where pupils must identify the missing number in an equation.

Pupils engage in a discussion about word problems and open sentences.

STEP 2 – EXPLANATION

Uses examples of story problems to create open sentences. Example: "John has some apples. He buys 3 more apples. Now he has 10 apples. How many apples did John have originally?"

Pupils create equations from story problems and solve for the missing number.

STEP 3 – DEMONSTRATION

Solves story problems by converting them into open sentences and finding the unknown variable.

Pupils solve word problems by creating and solving open sentences.

STEP 4 – NOTE TAKING

Pupils take notes on how to solve word problems by writing open sentences.

Pupils write down the steps for solving word problems.

NOTE:

  • Story problems can be written as open sentences that need to be solved.
  • Example: John + 3 = 10 → John = 10 - 3 → John = 7 apples.

EVALUATION:

  1. Write an open sentence for the problem: "Jane has 5 chocolates. She buys 4 more. How many chocolates does she have now?"
  2. Solve for the missing number: 6 + x = 14.

CLASSWORK:

  1. Create an open sentence for the problem: "Tom had 8 pencils. He gave 3 pencils to his friend. How many pencils does he have left?"
  2. Solve for x: 5 + x = 12.

ASSIGNMENT:

  1. Write an open sentence for the problem: "Mary has some marbles. She buys 5 more. Now she has 13 marbles. How many marbles did she have originally?"
  2. Solve for x: 10 - x = 6.

 

PERIOD 5:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1 – INTRODUCTION

Reviews all the types of open sentences and their real-world applications.

Pupils recall types of open sentences.

STEP 2 – EXPLANATION

Explains that open sentences are commonly used in everyday situations. Provides examples from shopping, time, and sharing.

Pupils listen and create their own open sentences.

STEP 3 – DEMONSTRATION

Gives examples of real-life open sentences. Example: "You have 5 Naira, and you buy a drink for 3 Naira. How much change do you get?"

Pupils work in groups to create and solve their own real-life open sentences.

STEP 4 – NOTE TAKING

Pupils write down real-life examples and their corresponding open sentences.

Pupils take notes in their notebooks.

NOTE:

  • Open sentences help us find unknowns in everyday problems.
  • Example: You have 15 Naira, buy an item for 10 Naira, how much change do you get?
  • Answer: 15 - 10 = 5 Naira.

EVALUATION:

  1. Solve for x: 10 + x = 15.
  2. Solve for y: 5 × y = 25.

CLASSWORK:

  1. Write an open sentence for this problem: "You have 3 toys, and you buy 2 more. How many toys do you have now?"
  2. Solve for y: 4 + y = 12.

ASSIGNMENT:

  1. Write an open sentence for this problem: "You have 10 pencils, and you give 4 to your friend. How many pencils do you have left?"

Solve for x: 8 + x = 14.