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

### MATHEMATICS

THIRD TERM

WEEK 2

PRIMARY 4

THEME – MENSURATION AND GEOMETRY

PREVIOUS LESSON –

**TOPIC – LENGTH **

**LEARNING AREA**

1. Introduction

2. Estimate and Measure the Length of Objects

3. Concept of Length and Its Standard Units

4. Relationship Between Metric Units

5. Addition and Subtraction in Cm, M and Km

6. Total Distance

7. Lesson Evaluation and Weekly Assessment (Test)

**LEARNING OBJECTIVES **

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

1. estimating and measuring the lengths of objects.

2. converting metres to centimetres.

3. converting centimetres to metres.

4. measuring distances in kilometres.

5. converting metres to kilometres.

6. Converting kilometres to metres.

7. adding and subtracting length.

**ENTRY BEHAVIOUR**

The pupils understand the concept of measuring in fashion design and carpentry.

**INSTRUCTIONAL MATERIALS**

The teacher will teach the lesson with the aid of tape rule, measuring tape and chart showing relationship between centimetres, metres and kilometres.

**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 – MEASUREMENTMeasure and record the lengths of the desk, plain sheet, textbook surface.

Desk

- Length 1 –

- Length 2 –

Plain sheet

- Length 1 –

- Length 2 –

Textbook

- Length 1 –

- Length 2 –

ACTIVITY 2 – CONCEPT OF LENGTH

Length is the measurement of distance from one point to other side of an object.

Length is measured in centimetres and millimetres, metres and kilometres.

A kilometer (km), meter (m), and centimeter (cm) are the standard units of length.Centimetres and millimetres are used for measuring short distances while metres and kilometres are used for measuring long distances.

SYNONYMS FOR LENGTHBreadth (width) and height are commonly used as length.

RELATIONSHIP LENGTH, BREADTH AND HEIGHTLength refers how long is the object.

Breadth (width) refers how short is the object.

Height refers how tall is the object.

Length and breadth are used for 2 dimensional shapes while length, breadth and height are used for 3 dimensional shapes.

ACTIVITY 3 – ESTIMATING AND MEASURING DISTANCES IN CENTIMETRESMaterials – Rulers , tape rules, indomine carton and a bigger one such as for refrigerator or generator.

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

- make a rough estimate of each material.

- measure the length in centimetres using standard tools for measurement.

- record and compare both measurements.

- estimate and measure the length, breadth and height of the classroom.

Note – Teacher lets pupils measure the length and breadth of the classroom but take charge of the height. Pupils safety first.

ASSIGNMENTFind out the length, breadth or height of the following,

- Door

- Window

LESSON 2 - CENTIMETRES, METRES AND KILOMETRES

ACTIVITY 1 – CONCEPTS OF CENTIMETRES, METRES AND KILOMETRES

- Centimeter (cm) is a metric unit of length that equals one hundredth of a meter. That’s, 100 cm = 1 m

- Meter (m) is a metric unit of length that equals one hundred of a centimeter. That’s, 1 m = 100 cm.

- Kilometer (km) is a metric unit of length that’s equal to one thousand of a metres. That’s, 1 km = 1000 m

ACTIVITY 2 – CONVERTING CM TO M (100 CM = 1 M)

Working Example 1Convert 100 cm to meters.

1st, divide the number of centimeters by 100,

100 ÷ 100 = 1

2nd, change the unit to meter.

100 cm = 1 m

Working Example 2Convert 253 cm to metre.

1st, divide the number of centimeters by 100,

253 ÷ 100 = 2.53

2nd, change the unit to meter.

253 cm = 2.53 m or

2 m 53 cm

Working Example 3Convert 23 cm to metre.

1st, divide the number of centimeters by 100,

23 ÷ 100 = 0.23

2nd, change the unit to metre,

23 cm = 0.23 m

Working Example 4Convert 9 cm to metre.

1st, divide the number of centimeters by 100,

9 ÷ 100 = 0.09

2nd, change the unit to metre,

9 cm = 0.09 m

WORKING EXERCISEConvert the following to metres,

1. 25 cm

2. 125 cm

3. 328

SOLUTIONS1.

25 cm= 25 ÷ 100 =0.25 m

2.

125 cm= 125 ÷ 100 =1.25 mor1 m 25 cm3.

328 cm= 328÷ 100 =3.28 mor3 m or 28 cm

ACTIVITY 3 – CONVERTING M TO CM (1 M = 100 CM)

Working Example 1Convert 5 m to centimetres.

1st, multiply the number by 100,

5 x 100

2nd, change the unit to centimetres,

5 m = 500 m

Working Example 2Convert 2.3 m to centimetres.

1st, multiply the number by 100,

2.3 x 100 = 230

2nd, change the unit to centimetres,

2.3 m = 230 cm

Working Example 3Convert 0.8 m to centimetres.

1st, multiply the number by 100,

0.8 x 100 = 80

2nd, change the unit to centimetres,

0.8 m = 80 cm

WORKING EXERCISESConvert the following to centimetres,

1. 11 m

2. 7.9 m

3. 0.61 m

SOLUTIONS1.

11 m= 11 x 100 =1100 cm2.

7.9 m= 7.9 x 100 =790 cm3.

0.61 m= 0.61 x 100 =61 cm

LESSON 3 - CONVERTING M TO KM AND KM TO M

ACTIVITY 1 – CONVERT M TO KM (0.001 M = 1 KM)

Working Example 1Convert 9000 m to kilometres.

1st, divide the number of metres by 1000,

9 000 ÷ 1000 = 9

2nd, change the unit to kilometres,

9 000 m = 9 km

Working Examples 2Convert 632 m to kilometres.

1st, divide the number of metres by 1000,

632 ÷ 1000 = 0.632

2nd, change the unit to kilometres,

632 m = 0.632 km

Working Examples 3Convert 52 m to kilometres.

1st, divide the number of metres by 1000,

52 ÷ 1000 = 0.052

2nd, change the unit to kilometres,

52 m = 0.052 km

Working Examples 4Convert 6 m to kilometres.

1st, divide the number of metres by 1000,

6 ÷ 1000 = 0.006

2nd, change the unit to kilometres,

6 m = 0.006 km

WORKING EXERCISESConvert the following metre to centimetres,

1. 5 m

2. 25 m

3. 326 m

4. 1 020 m

SOLUTIONS1.

5 m= 5 ÷ 1 000 =0.005 km2.

25 m= 25 ÷ 1 000 =0.025 km3.

326 m= 326 ÷ 1 000 =0.326 km4.

1 020 m= 1020 ÷ 1 000 =1.02 km

ACTIVITY 2 – CONVERT KM TO M (1 KM = 1 000 M)

Woking Example 1Convert 3 km to metres.

1st, multiply the number by 1 000,

3 x 1 000 = 3 000

2nd, change the unit to metres,

3 km = 3 000 m

Woking Example 2Convert 1.5 km to metres.

1st, multiply the number by 1 000,

1.5 x 1 000 = 0.0015

2nd, change the unit to metres,

1.5 km = 0.0015 m

Woking Example 3Convert 0.9 km to metres.

1st, multiply the number by 1 000,

0.9 x 1 000 = 900

2nd, change the unit to metres,

0.9 km = 900 m

WORKING EXERCISESConvert the following to metres,

1. 5 km

2. 6km 100 m

3. 0.78 km

SOLUTIONS1. 5 km = 5 x 1 000 = 5 000 km

2. 6km 100 m = 6 x 1 000 + 100 = 6 000 + 100 = 6 100 m

3. 0.78 km = 0.78 x 1 000 = 780 km

LESSON 4 - ADDITION AND SUBTRACTION INVOLVING CM, M AND KM

ACTIVITY 1 – ADDITION INVOLVING CM, M AND KM

Working Example 1A. Measure the following lines.

_______________________ cm

__________________________________________ cm

B. Add the two lines together.

C. Convert the result in B to metres.

SOLUTIONA. Lets assumed the lines is 58 cm and 73 cm respectively.

B. Add 58 cm and 73 cm

¹5 8 cm

+ 7 3 cm

_________

1 3 1 cm

C. Convert 131 cm to metre.

131 cm= 131 ÷ 100 = 1.31 =1.31 mor1 m 31 cm

Working Example 2Add 5 m 56 cm and 8 m 69 cm

¹5 m 56 cm

+ 8 m 59 cm

______________

14 m 05 cm

Working Example 3Add 5 km 674 m and 3 km 475 m together.

¹5 km ¹674 m

+ 3 km 475 m

______________

9 km 149 m

WORKING EXERCISESAdd the following:

1. 9 125 m and 6 786 m

2. 4 804 m, 3.498 km and 2 397 m

3. 989 m and 483 m

4. 2.168 km + 700 m

5. 6 m 71 cm and 5 m 92 cm

SOLUTIONS1. 9 125 m and 6 786 m

9 125 m

+ 6 786 m

______________

15 911 m

Therefore, 9 125 m + 6 786 m =

15 911 mor15 km 912 mor15.912 km

2. 4 804 m, 3.498 km and 2 397 m

¹4 804 m

(3.498 km = 3 498 m), + 3 498 m

+ 2 397 m

______________

10 699 m

Therefore, 4 804 m + 3.498 km + 2 397 m =

10 699 mor10 km 699 mor10.699 km

3. 989 m and 483 m

¹989 m

+ 483 m

______________

1 472 m

Therefore, 989 m + 483 m =

1 472 mor1 km 483 mor1.472 km

4. 2.168 km + 700 m

2.168 km

(700 m = 0.700 km) + 0.700 km

______________

2.868 km

Therefore, 2.168 km + 700 m = 2.878 km or 2 km 878 m or 2 878 m

5. 6 m 71 cm + 5 m 92 cm

¹6 m 71 cm

+ 5 m 92 cm

______________

12 m 63 cm

Therefore, 6 m 71 cm + 5 m 92 cm =

12 m 63 cmor12.63 mor1 263 cm

ACTIVITY 2 – SUBTRACTION INVOLVING CM, M AND KM

Working Example 1Subtract 9 m 56 cm and 8 m 69 cm

9 m 56 cm

– 8 m 59 cm

______________

97 cm

Therefore, 9 m 56 cm – 8 m 69 cm = 97 cm or 0.97 m

Working Example 24 804 m + 3.498 km – 2 397 m

4 804 m

(3.498 km = 3 498 m), + 3 498 m

______________

8 302 m

– 2 397 m

______________

5 905 m

Therefore, 4 804 m + 3.498 km – 2 397 m = 5 905 m or 5 km 905 m or 5.905 km

Working Example 3989 m – 483 m

989 m

– 483 m

______________

506 m

Therefore, 989 m – 483 m = 506 m or 5.06 km

Working Example 42.168 km – 700 m

2.168 km

(700 m = 0.700 km) – 0.700 km

______________

1.468 km

Therefore, 2.168 km – 700 m = 1.468 km or 1 km 468 cm

LESSON 5 - WORD PROBLEMS

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

Working Example 1A man travels from Lagos to Ibadan in 15.7 km, Ibadan to Ilorin in 29.1 km and Ilorin to Abuja 34.9 km.

- What is the total distance traveled?

- Find the average distance traveled.

Solution,

Total distance is,

15.7 km

+ 29.1 km

+ 34.9 km

____________

79.7 km

Average distance is,

79.7

_______ 26.6 km

3

Working Example 2A man walks 150 kilometres in 5 hours. How long does he work in,

- 3 hours

- 8 hours

- 12 hours

Solution,

In one hour, he walks in

150

_________ = 30 km

5

- In 3 hours, 3 x 30 = 90 km

- In 8 hours, 8 x 30 = 240 km

- In 12 hours, 12 x 30 = 360 km

Working Example 3A boy can walk a distance of 100 km in 20 hours . Find the average distance.

100

_________ = 5 km

20

WORKING EXERCISES1. A man travels from Lagos to Ilorin in 25.7 km, Ilorin to Abuja in 79.1 km and Ilorin to Kaduna 64.9 km.

- What is the total distance traveled?

- Find the average distance traveled.
2. A man can walk a distance of 280 km in 12 hours . Find the average distance.

3. A man walks 360 kilometres in 5 hours. How long does he work in,

- 3 hours

- 8 hours

- 12 hours

**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 measuring tape and rule.

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

Pupil’s Activities – State the uses of ruler and measuring tape.

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

Pupil’s Activities – Mention the fashion designer, carpentry, welder, surveyor, builder, etc.

6. Teacher uses the pupil’s responses to introduce the lesson and guides pupils to measure each side of their maths textbook with ruler.

Pupil’s Activities – Pay attention to the lesson introduction and measure the lengths of the maths textbook.

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

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

8. Teacher guides pupils to measure the length, breadth and height of carton of different sizes.

9. Teacher leads pupils to measure the length and breadth of the classroom.

Pupil’s Activities – Participate actively in measuring activities.

10. Teacher discuss the relationship between standard units of length.

11. Teacher guides pupils to convert cm to m, m to cm, m to km and km to m.

Pupil’s Activities – Follow the teacher’s instructions to convert cm to m, m to cm, m to km and km to m.

12. Teacher guides pupils to add and substrate length in cm, m and km.

Pupil’s Activities – Follow the teacher’s guides to add and substrate length in cm, m and km.

13. Teacher leads pupils to calculate total distance.

Pupil’s Activities – Find the total distance.

14. 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. estimate and measure the lengths of objects.

2. convert metres to centimetres.

3. convert centimetres to metres.

4. measure distances in kilometres.

5. converting metres to kilometres.

6. convert kilometres to metres.

7. adding and subtracting length.

8. find the distance.