# Open Sentences (Primary 5 and Primary 6)

Last Updated on July 26, 2020 by Alabi M. S.

**MATHEMATICS**

**SECOND TERM/WEEK 3/PRIMARY 5**

**THIRD TERM/WEEK 2/PRIMARY 6**

**TOPIC: OPEN SENTENCES**

**PERFORMANCE OBJECTIVES**

By the end of the lesson, the pupils should have attained the following objectives (cognitive, affective and psychomotor):and should be able to –

1. solve problems expressed as open sentence;

2. interpret words in open sentences and solve them;

3. solve related problems on quantitative aptitude.

**ENTRY BEHAVIOR**

Addition, subtraction, multiplication and division.

**INSTRUCTIONAL MATERIALS**

The teacher will teach the lesson with the aid of open sentence charts

*METHOD OF TEACHING – Choose a suitable and appropriate methods for the lessons.*

*Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons. *

**REFERENCE MATERIALS**

Scheme of Work

9 – Years Basic Education Curriculum

Course Book

All Relevant Material

Online Information

**CONTENT OF THE LESSON**

**LESSON ONE – INTRODUCTION**

Pupil’s Activities 1 – Fill in the brackets.1. 12 + (___) = 25

2. 45 – (___) = 32

3. (___) x 5 = 45

4. 45/(___) = 5

Pupil’s Activities 2 – Confirm the following statements (if True or False) and interpret them in numbers. Read and interpret the statement to confirm if the statements are true or false.1. Five plus two equal to seven.

5 + 2 = 7, true

2. Twenty three minus five equal to fifty.

23 – 5 = 50, false.

3. Four multiple by four equal to eighteen.

4 x 4 = 18, false.

4. Nine divided by two equal four.

9/2 = 4, false.

Teacher’s remark – The above are known as open sentences. An open sentence can be either true or false depending on what values are used.

Pupil’s Activities 3 – In the activities 2, correct the sentences 2 to 4.2. 23 – 5 = 18

3. 4 x 4 = 16

4. 9/2 = 4.5

**LESSON TWO – OPEN SENTENCES INVOLVED ADDITION AND SUBTRACTION**

Teacher’s review – Open sentences, closed sentences and equation.

3 + (___) = 8. This is an open sentence.

When 5 is written in the circle, the sentence is closed and true.

If 2 is written in the circle, the sentence would be closed but false.

3 + M = 8 is also called equation.

**Note – When we find the number that goes in for the letter to make the equation true, we say we have solved the equation.**

Pupil’s Exercises – Solve these equations (10 minutes)1. 5 + A = 12

2. 29 – 19 = B

3. 93 – C = 74

4. D + 9 = 41

5. E + 1.6 = 7.2

6. 8.3 – 3.8 = F

7. 4.8 + 9.6 = G

**Teacher’s/Pupil’s Activities – Marking and Correction **

**LESSON THREE – OPEN SENTENCES INVOLVING MULTIPLICATION AND DIVISION**

**Pupil’s Exercises – Solve these equations**

1.13 x X = 169

2. 3A + 9 = 12, 3A + 9 = 3 x A + 9

3. 7C = 21, 7C is the same as 7 x C = 21

4. 10 = (4 x Z) + 5

5. 2/5 x Y =40

6. 100 ÷ R = 5

Teacher’s Activities – Guides the pupils through the difficult questions.

**LESSON FOUR – SENTENCES AND EQUATIONS**

The letter in an equation is called an unknown.

Teacher’s/Pupil’s ActivitiesSolve this equation:

1. 2a = 7;

2. 7 + a = 14.

SOLUTIONS1. 2a = 7

2. 7 + a = 142 x a = 7

Subtract 7 from both sidesDivide both sides by 2

7 – 7 + a = 14 – 72a/2 = 7/2

a = 7a = 3 ½

Pupil’s Exercises

Find the unknown letters:

1. d – 32 = 51

2. 29 – d = 6

**LESSON FIVE – WORD PROBLEMS ON OPEN SENTENCES**

**Teacher’s/Pupil’s Activities 1 – A number is multiply by 4 and 5 is added to it, the result is 21. What is the number?**

**SOLUTION**

A number is multiply by 4 and 5 is added to it, the result is 21. What is the number?

Let ‘a’ be the number.

It is multiplied by 4,

i.e. 4 x a = 4a

5 is added to it,

i.e. 4a + 5

The result is 21

i.e. 4a + 5 = 21

The statement is 4a + 5 = 21

Subtract 5 from both sides

4a + 5 – 5 = 21 – 5

4a = 16

Divide both sides by 4

4a/4 = 16/4

a = 4

**Pupil’s Exercises/Assignments**

1. If 60 oranges are divided equally in 3 baskets, how many oranges are in one basket?

2. The difference between two numbers is 250. If the smaller is 135, what is the other number?

3. If I substrate 14 from a certain number the answer is 45, what is the number?

4. A certain number added to itself gives an answer of 22. Find the number.

**PRESENTATION**

To deliver the lesson, the teacher adopts the following steps:

1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the pupils some questions;

2. Guides pupils to solve open sentences involving addition, subtraction, multiplication and division;

Pupil’s Activities – Solve open sentences involving addition, subtraction, multiplication and division;

3. Guides pupils to interpret and solve word problems e.g. if 60 oranges are divided equally in 3 baskets, how many oranges are in one basket?

Pupil’s Activities – Interpret word problems into open sentences and solve them.

4. Guides pupils to solve quantitative aptitude related problems involving three or more arithmetic operations in a sample.

Pupil’s Activities – Solve quantitative aptitude problems involving three or more arithmetic operations in a sample.

**CONCLUSION**

To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson.

**LESSON EVALUATION **

**Pupils to:**

1. interpret word problems into open sentences and solve them;

2. pupils to solve quantitative aptitude problems involving at least three arithmetic operations in a sample.