# Weight – Addition, Subtraction, Multiplication and Division of Weight in Grams and Kilograms Primary 4 (Basic 4) Term 3 Week 3 Mathematics

### MATHEMATICS

THIRD TERM

WEEK 3

PRIMARY 4

THEME – MENSURATION AND GEOMETRY

PREVIOUS LESSON – Length – Estimation of Length and Its Comparison with Actual Measurement Primary 4 (Basic 4) Term 3 Week 2 Mathematics

**TOPIC – LENGTH **

**LEARNING AREA**

1. Introduction

2. Standard Units it Weight

3. Addition and Subtraction of Weight in g and kg

4. Multiplication and Division of Weight in g and kg

5. Word Problems

6. Lesson Evaluation and Weekly Assessment (Test)

**LEARNING OBJECTIVES **

By the end of the lesson, most pupils should have attained the following objectives –

1. identify the standard unit for weight measurement.

2. convert kilograms to grams and grams to kilograms.

3. carry out simple addition and subtraction involving kilogram and grams.

4. carry out simple multiplication and division involving kilogram and grams.

5. word problems involving, addition, subtraction, multiplication and division in g and kg.

**ENTRY BEHAVIOUR**

The pupils can identify objects with different weights.

**INSTRUCTIONAL MATERIALS**

The teacher will teach the lesson with the aid of kitchen, weighing and body scales.

**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**

1. Scheme of Work

2. 9 – Years Basic Education Curriculum

3. Course Book

4. All Relevant Material

5. Online Information

CONTENT OF THE LESSON

LESSON 1 - INTRODUCTION

ACTIVITY 1 – CONCEPTS OF WEIGHT

Weight is the amount of matter in a body or object.It measures how light or heavy an object is.

That’s, the different between weight of objects is how an object is lighter or heavier to another.

The standard or metric units of weight are gram (g) and kilogram (kg).

A gram (g) is the unit of weight that’s used to measure lighter objects while a kilogram (kg) is used to measure objects that are heavy.

The relationship between gram and kilogram is,

1 000 g = 1 kg

ACTIVITY 2 – MEASUREMENT OF OBJECTS OR BODYMaterials – scale and body scale.

Teacher organizes pupils in groups or pairs depending on the size of the class to,

- measure and compare the weight of two or more objects such sachet of water, bottle water, coke, school bag, textbooks, etc.

- measure and record their body weight.

ACTIVITY 3 – CONVERSION OF G TO KG

Working Example 1Convert 5 000 g to kilograms.

1st, divide the number of gram by 1 000,

5 000 ÷ 1 000 = 5

2nd, change the unit to kilograms,

5 000 g = 5 kg

Working Example 2Convert 3 765 g to kilograms.

1st, divide the number of gram by 1 000,

3 756 ÷ 1 000 = 3.756

2nd, change the unit to kilograms,

3 756 g = 3.756 kg

Or

3 kg 756 g

Working Example 3Convert 167 g to kilograms.

1st, divide the number of gram by 1 000,

167 ÷ 1 000 = 0.167

2nd, change the unit to kilograms,

167 g = 0.167 kg

Working Example 4Convert 13 g to kilograms.

1st, divide the number of gram by 1 000,

13 ÷ 1 000 = 0.013

2nd, change the unit to kilograms,

13 g = 0.013 kg

Working Example 5Convert 9 g to kilograms.

1st, divide the number of gram by 1 000,

9 ÷ 1 000 = 0.009

2nd, change the unit to kilograms,

9 g = 0.009 kg

WORKING EXERCISES/ASSIGNMENTCovert the following to kilograms,

1. 0.9 g

2. 135 g

3. 0.048 g

4. 8 787 g

5. 1.25 g

SOLUTIONS1. 0.9 g = 0.9 x 1 000 = 0.0009 kg

2. 135 g = 135 x 1 000 = 0.135 kg

3. 0.048 g = 0.048 x 1 000 = 0.00048 kg

4. 8 787 g = 8 787 x 1 000 = 8.787 kg

5. 1.25 g = 1.25 x 1 000 = 0.00125

ACTIVITY 4 – CONVERSION OF KG AND G

Working Example 1Convert 9 kg to grams.

1st, multiply the number of kg by 1 000,

9 x 1 000 = 9 000

2nd, change the unit of grams

9 kg = 9 000 g

Working Example 2Convert 1.5 kg to grams.

1st, multiply the number of kg by 1 000,

1.5 x 1 000 = 1 500

2nd, change the unit of grams

1.5 kg = 1 500 g

Working Example 3Convert 0.73 kg to grams.

1st, multiply the number of kg by 1 000,

0.73 x 1 000 = 730

2nd, change the unit of grams

0.73 kg = 730 g

Working Example 4Convert 5 kg 7 g to grams.

1st, multiply the number of kg by 1 000,

5 x 1 000 + 7 = 5 007

2nd, change the unit of grams

5 kg 7 g = 5 007 g

WORKING EXERCISES/ASSIGNMENTComplete the following:

1. 7 368 g = ________ kg

2. 9.515 kg = ________ g

3. 1.2 g = ________ kg

4. 1 kg 98 g = ________ kg

5. 1 kg 98 g = ________ g

LESSON 2 - ADDITION AND SUBTRACTION OF WEIGHTS

ACTIVITY 1 – ADDITION OF WEIGHTS

Working Example 1Teacher asks each group or pair to add their body weights together.

Lets assume the weight of five pupil in a group are as follows: 25.6 kg, 28.5kg, 27.3 kg, 26.1 kg and 24 kg.

25.6 kg + 28.5kg + 27.3 kg + 26.1 kg + 24 kg =

25.6 kg

+ 28.5kg

+ 27.3 kg

+ 26.1 kg

+ 24.0 kg

______________

131.5 kg

The weight of pupils in group A is 131.5 kg.

Working Example 2Add 6 kg 950 g to 2 kg 715 g

6 kg 950 g

+ 2 kg 715 g

_____________

9 kg 665 g

Working Example 3Add 5 kg 56 g and 8 kg 69 g

¹5 kg 56 g

+ 8 kg 59 g

______________

14 kg 05 g

Working Example 4Add 5.674 kg and 3.475 kg together and leave your answer in grams.

5.674 kg

+ 3. 475 kg

______________

9.149 kg

Therefore, 9.149 kg = 9.149 x 1 000 = 9 149 g.

WORKING EXERCISESAdd the following:

1. 9 125 g and 6 786 g

2. 4 804 g, 3.498 kg and 2 397 g

3. 989 g and 483 g

4. 2.168 kg + 700 g

5. 6 kg 71 g and 5 kg 92 g

SOLUTIONS1. 9 125 g and 6 786 g

9 125 g

+ 6 786 g

______________

15 911 g

Therefore, 9 125 g + 6 786 g =

15 911 gor15 kg 912 gor15.912 kg

2. 4 804 g, 3.498 kg and 2 397 g

¹4 804 g

(3.498 kg = 3 498 g), + 3 498 g

+ 2 397 g

______________

10 699 g

Therefore, 4 804 g + 3.498 kg + 2 397 g =

10 699 gor10 kg 699 gor10.699 kg

3. 989 g and 483 g

¹989 g

+ 483 g

______________

1 472 g

Therefore, 989 g + 483 g =

1 472 gor1 kg 483 gor1.472 kg

4. 2.168 kg + 700 g

2.168 kg

(700 g = 0.700 kg) + 0.700 kg

______________

2.868 kg

Therefore, 2.168 kg + 700 g = 2.878 kg or 2 kg 878 g or 2 878 g

5. 6 kg 71 m + 5 kg 92 m

6 kg 71 g

+ 5 kg 92 g

______________

11 kg 163 g

Therefore, 6 kg 71 g + 5 kg 92 g =

11 kg 163 gor11.163 kgor11 163 g

ACTIVITY 2 – SUBTRACTION INVOLVING WEIGHT

Working Example 1Subtract 9 kg 156 g and 8 kg 569 g

9 kg 156 g

– 8 kg 569 g

______________

587 g

Therefore, 9 m 156 cm – 8 m 569 cm = 587 g or 0.587 kg

Working Example 24 804 g + 3.498 kg – 2 397 g

4 804 g

(3.498 kg = 3 498 g), + 3 498 g

______________

8 302 g

– 2 397 g

______________

5 905 g

Therefore, 4 804 g + 3.498 kg – 2 397 g = 5 905 g or 5 kg 905 g or 5.905 kg

Working Example 3989 g – 483 g

989 g

– 483 g

______________

506 g

Therefore, 989 g – 483 g = 506 g or 0.506 kg

Working Example 42.168 kg – 700 g

2.168 kg

(700 g = 0.700 kg) – 0.700 kg

______________

1.468 kg

Therefore, 2.168 kg – 700 g = 1.468 kg or 1 kg 468 g

LESSON 3 - MULTIPLICATION AND DIVISION INVOLVING WEIGHT

ACTIVITY 1 – MULTIPLICATION OF WEIGHT

Working Example 130 kg x 5

3 0

x 5

_______

1 5 0

Therefore, 30 kg x 5 = 150 kg

Working Example 2170 g x 9

1 7 0

x 9

_______

1 5 3 0

Therefore, 170 g x 9 = 1 530 g

Working Example 312.567 kg x 4

12.567

x 4

_______

50.268

Therefore, 12.567 kg x 4 = 50.268 kg.

Working Example

31 kg 855 g x 5

31 kg 855 g

x 5

_____________

159 kg 275 g

Therefore, 31 kg 855 g x 5 = 159 kg 275 g.

ACTIVITY 2 – DIVISION OF WEIGHT

Working Example 1Divide 33 kg 720 g by 6

Therefore, 33 kg 720 g ÷ 6 = 5 kg 620 g

Working Example 225 kg 376 g ÷ 8

Therefore, 25 kg 376 g ÷ 8 = 3 kg 172 g

Working Example 323.049 kg ÷ 9

Therefore, 23.049 kg ÷ 9 = 2.561 kg

Imagine source – New Method Mathematics Book 4

LESSON 4 - WORD PROBLEMS

Word problems are mathematical problems presented a simple language rather than in mathematical notation.

Working Example 1The weight of a bag of pure water is 7.15 kg. Some of satchels of water are removed and their weight is 2.68 kg, what is the weight of the remaining satchels?

Solution,

7.15 kg

– 2.68 kg

____________

The weight of the remaining satchels of water is 5.47 kg

Working Example 2Treasure bought 10 kg 251 g of yams. He bought 8 kg 675 g more. What is the total weight of yams?

Solution,

10 kg 251 g

+ 8 kg 675 g

____________

The total weight of yams is 18 kg 826 g

WORKING EXERCISES1. Caleb weighs 2.235 kg more than Demilade. If Demilade weighs 84.0 kg, find Caleb’s weight.

2. Caleb weighs 2.235 kg less than Demilade. If Demilade weighs 84.0 kg, find Caleb’s weight.

3. The weight of 5 exercise books is 3.94 kg. 3 of them weigh 2.6 kg. Find the weight of the remaining exercise book.

4. What is 15.38 kg plus 73.4 kg?

5. What is 15.38 kg minus 73.4 kg?

6. What is 15 kg divided by 3?

7. What is 26 g multiply 25?

LESSON 5 - REVISION

**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. Teacher organizes the pupils in groups or pair depending on the size of the class.

3. Teacher displays kitchen scale, weighing scale and body scale.

4. Teacher asks the groups or pairs to discuss the uses of the scales with appropriate examples.

Pupil’s Activities – State the uses of each of the scale.

5. Teacher asks pupils to state the places where the tools are commonly used.

Pupil’s Activities – Mention the supermarket, hospital, abattoir, freeze food store, etc.

6. Teacher uses the pupil’s responses to introduce the lesson and guides pupils to measure each of the following: satchels of pure water, bottle of coke, satchel of salt, etc.

Pupil’s Activities – Pay attention to the lesson introduction and measure the weight of satchels of pure water, bottle of coke, satchel of salt, etc.

7. Teacher uses the results of their measurement to discuss the concept of weight and its standard units.

Pupil’s Activities – Explain the meaning of weight and the relationship between its standard units.

8. Teacher lets pupils to measure and record the weight of their bodies.

Pupil’s Activities – Check and record their bodies.

9. Teacher discuss the relationship between standard units of weight.

Pupil’s Activities – Mention 1 000 g = 1 kg

10. Teacher guides pupils to convert g to kg and kg to g.

Pupil’s Activities – Follow the teacher’s instructions to convert kg and kg to g.

11. Teacher guides pupils to add and substrate weight in g and kg.

Pupil’s Activities – Follow the teacher’s guides to add and substrate weight in g and kg.

12. Teacher leads pupils to interpret and solve simple word problems on weight.

Pupil’s Activities – Solve word problem questions.

13. Teacher summarizes each of the lesson on the board with appropriate evaluation.

Pupil’s Activities – Participate actively in the summary of the lesson by responding correctly in the questions and write as instructed.

**CONCLUSION**

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

### NEXT LESSON

**LESSON EVALUATION **

Teacher asks pupils to,

1. identify the standard unit for weight measurement.

2. convert kilograms to grams and grams to kilograms.

3. carry out simple addition and subtraction involving kilogram and grams.

4. carry out simple multiplication and division involving kilogram and grams.

5. word problems involving, addition, subtraction, multiplication and division in g and kg.