Mathematics Lesson notes for primary 4 Third Term

WEEK 1

TOPIC: ESTIMATING LENGTH AND COMPARING MEASUREMENT

SUBTOPIC: ADDITION AND SUBTRACTION OF LENGTH

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

1. Estmate distance in kilo meter and meters.

2. Add lengths to kilo meters and meters

3. Solve quantitative aptitude problems on length.

CONTENT

ESTIMATING LENGTH AND COMPARING MEASUREMENT

To estimate means to give an approximate, rather than an exact figure. It means

Making a guess that is accurate or near accurate. Either way, be sure to estimate.

Do not shy away from giving estimates. Practice regularly until you can estimate short

lengths in cm with accuracy.

Converting meters to kilometers and vice versa

Nasif lives in the village. He walks to the school which is about half a kilometre from the

village. It takes him about 8 minutes to walk to school.

1 kilometre (km) = 1000 metres (m).

So Nasif walks 500 metres to school.

Long distances are measured in kilometres. Think of distances that are measured in

kilometres. The length of rivers, the distance from one city to another, the rail track, etc.

Examples

Study these examples of converting kilometres to metres.

Example 1: 2 km to metres

=2×100

=2000 meters

Example 2: 4 km 250 m to meters

= (4×1000m)+250m

=4000m+250m

=4250m

Example 3:4.758m

4.758×1000

=4758m

Exercise 2

A. Convert the following to meters.

1.8 km 2.9 km 3.10 km 4.7 km 615 m 5.6 km 400m 6.1 km 625 m 7.2 km 19 m 8.15 km 215 m 9.3 km 100 m 10.8 km 23 m

B .Convert the following to meters.

1.716 km 2.5.782 km 3.2.139 km 4.8.791 km 5.0.920 km 6.7.1 km 7.5.4 km 8.9.7 km 9.0.09 km 10.4.7 km

To change from metres to kilometres you divide by 1000.

Examples

1.Convert 1586 m to kilometre

1586 ÷ 1000

1586 km = 1.586 km =

1 km 586 m

2.Convert 678 m to kilometres

678 ÷ 1000

678.0 km = 0.678 km = 0 km 678 m

Exercise 3

A. Express in kilometres. Remember the position of the decimal point.

1.345 m 2.150 m 3.755 m 4.48 m 5.66 m 6.495 m 7.899 m 8.675 m 9.4 m 10.95 m

B. Convert the following to kilometres and metres.

1.9600 metres 2.8800 metres 3.4525 metres 4.3333 metres 5.1750 metres 6.6112 m 7.7009 m 8.2010 m 9.3165 m10. 1038 m

ADDITION INVOLVING LENGTH

A B

C D

Line AB is 13 centimetres long while, line CD is 9 centimetres long.

We write AB = 13 cm

CD = 9 cm

The total length of two lines is: 13 cm + 9 cm = 22cm

The difference in their length is: 13 cm −9 cm = 4 cm

We write these as:

AB + CD = 13 cm + 9 cm = 22 cm and AB −CD = 13 cm −9 cm = 4 cm

ADDITION OF LENGTHS IN KUILOMETERS AND METERS

7KM+3KM=

645+ 24m=

1.A swimming pool is 120 metres long. Michael swims 6 laps. What distance did he cover

in 6 laps?

2.The average weekly distance travelled by a marketer is 320 kilometres. How far does he travel in a year?

3.A limosine car is 800.5 cm long. Calculate its length in metres.

4.An oil pipe is to be made 16.8 m long. It is made into three equal sections.16.8m

a)How long is each section?

b)How long would each section be if it were split into seven equal sections?

5.a)Find one half of a ball of string measuring 21.2 m long.

b)Find one quarter of the same ball of string.

6.Kalu is walking to his friends house which is 10.5 kilometres away. He walks one-third of the distance and then takes a rest.

a)How far did he walk before taking a rest?

b)How far has he still to walk?

WEEK 2

TOPIC: WEIGHT

SUBTOPIC: ADDITION AND SUBTRACTION OF WEIGHT

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

1. Solve problems on weights of objects

2. Solve problems on the multiplication of weights in kg and gram

3. Weigh some objects in their classroom environment.

CONTENT

The standard unit of weight is the gram

Remember: 1 000 grams = 1 kilogram

i.e. 1 000 g = 1 kg

The gram is the unit of weight,

and is used to measure very small masses.

Converting kilogram and grams

To convert kilograms to grams, multiply by 1 000.

Examples

A. Convert to grams.

1. 9 kg 2. 1.5 kg 3. 0.048 kg

Solution

1. 9 kg = 9 ×1 000 g = 9 000g

2. 1.5 kg = 1.5 ×1 000 g = 1 500g

3. 0.048 kg = 0.048 ×1 000 g = 48g

Convert to grams.

1.2kg 350g 2.3kg 75kg 3.5kg 8g

Solution

1. 2kg 350g= 2 ×1000g + 350g

=2000+350g

=2350g

2. 3kg 75g= 3 ×1000g + 75g

= 3000g + 75g

= 3075g

3. 5kg 8g= 5×1000g+8g

=5000g+ 8g

=5008g

Exercise 1

Convert each of the following to grams.

1.4kg 2.1.25kg 3.5.504kg 4.0.75kg 5.2kg 121g 6.31\2kg 7.1kg 567g 8.71\ 10kg

ADDITION OF WEIGHT IN KILOGRAMS AND GRAMS

Here 6kg 940g has been added ton2kg 705g.

Solution:

Kg g

6 940

+2 705= 8kg 1645 Change 1645 to kg and grams

8kg 1645g=8kg +1kg+645g

=9kg 645g

245+416g=661g

Exercise 1

Add the following together.

1.2kg 371g and 5kg 258g 2.13kg 107g and 8kg 887 3.51g 47g and 36kg 69g 4.53.7kg and 34.85kg .5. 989g and 7kg 918g 6.26kg 55g and 3kg 69g 7.0.758kg and 0.587kg

SUBTRACTION OF WEIGHT IN KILOGRAMS AND GRAMS

Examples

1. Subtract 2kg 715g from 7kg 875g

Solution: 7kg 875g- 2kg 715g=5kg 124g

2. Subtract 13kg 76gfrom 37kg 161g

Solution:37kg 161g-7kg 875g=24kg 85g

Exercise

Subtract the following.

1.11kg 45g from 16kg 200g 2.5kg 140g from 9kg 345g 3.17.5kg from 20.3kg 4.1.881kg from 2kg

5.0.385kg from 1kg 6.3kg 48g from 5kg

Word problems involving addition and subtraction

Example

Mrs. Adoh has 567.5kg of beans in her shop. She sold 273.75kg. What weight of beans does she have left?kg

Weight of beans in the shop = 567.50

Weight of beans sold = –273.75

Weight of beans left = 293.75

Exercise

Solve the following word problems.

1. The weight of a bucket filled with water is 7.25kg. If the weight of the bucket is 1.75kg,

What is the weight of the water?

2 Take away 15.38kg from 73.4kg.

3. Take away 2.145kg from 2.645kg.

4. What is 5kg minus 3.257kg.

5.Comfort bought 15kg 250g of yam flour. She used 12kg 800g for a feast. What quantity of flour does she have left?

6.Adeoye weighs 2.235kg less than Bolaji. If Bolaji weighs 84.0kg, find Adeoye’s weight.

7.Sola weighs 63kg 725g and Sulaiman’s weight is 67kg 10g. Find their difference in weight.

8 Khadija weighs 29.5kg and Ngozi weighs 31.05kg. Find their difference in weight.

9.The weight of two bags containing yam flour and cassava flour is 9kg 25g. If one of the bags weighs 6kg 70g, what is the weight of the other?

10.The weight of three books is 3.54kg. Two of them weigh 2.6kg. Find the weight of the third book.

Multiplication of weight in kilograms and grams

Study these examples of multiplying weights.

Examples

1.Multiply 3kg 325g by 5

2.8kg 50g ×6

Solution: Note 1000g = 1kg

1. Kg g

3 325

× 5 =15kg 1625g.

Change 1625g t0 1g 625g

15kg + 1g + 625g

=16kg 625g

2. kg g

8 50

× 6 = 48kg 300g

Solve the following.

1.30kg 170g ×9 2.12kg 56g ×4 3.52kg 80g ×15 4.31kg 855g ×12

Division of weight in kilograms and grams

Study these examples of dividing weights.

Examples

1. Divide 33 kg 720 g by 6 2. 25 kg 376 g ÷ 8 3. 23.049 kg ÷ 9

1. 5 kg 620 g

6 33 kg 720 g

30 kg/ +3 000 g/

3 kg 3 720 g

– 36/

120

–120/

Thus 33 kg 720 g ÷ 6 = 5 kg 620 g

2. 3 kg 172 g

8 25 kg 376 g

24 kg +1 000 g/

1 kg 1 376 g

– 8̅̅̅̅̅̅/

– 56/

– 16\00

Thus 25 kg 376 g ÷ 8 = 3 kg 172 g

2.561 kg/

9 23.049 kg

– 18/

– 45/

– 54/

– 09/

Thus 23.049 kg ÷ 9 = 2.561 kg

Exercise

1. Divide 12 kg 260 g by 4 2. Divide 5 kg 200 g by 4 3. Divide 6 kg 360 g by 5

4. Divide 10 kg 260 g by 6 5. Divide 7 kg 263 g by 3 6. Divide 15 kg 366 g by 6

7. Divide 10 kg 989 g by 9 8. 41.976 kg ÷ 4 9. 17.152 kg ÷ 8

10. 21.315 kg ÷ 5

Unit 7

Word problems involving multiplication and division

Examples

1. A bag of cement weighs 50 kg. What is the total weight of 4 bags of cement?

Solution

× 4

200 kg

The total weight of 4 bags of cement is 200 kg.

2. Five women share 14.5 kg of maize equally. How much will each get?

Solution

2.9 kg/

5 14.5 kg

– 10/

– 45/

” Each woman will get 2.9 kg of maize

Exercise

1. Four cartons of soft drinks weigh 15 kg 316 g. How much will one carton weigh?

2. Find the total weight of 8 tins of paint if each weighs 1.75 kg.

3. A pair of shoes weighs 875 g. Find the weight of 12 similar pairs of shoes.

4. A sachet of gari weighs 255 g. Find the weight of 15 similar sachets of gari.

5. Eight women are to share 35 kg 232 g of rice equally among themselves. How much

does each woman get?

6. A man carried 5 bags of sand from one place to another. Each bag weighs 24.75 kg.

Find the total weight of sand carried by the man.

7. Find the weight of 14 concrete blocks if each weighs 14 kg.

8. 1 kg 449 g of powdered milk is shared among 9 pupils. How much will each receive?

9. Multiply 5 kg 37 g by 8.

10. Divide 123 kg 750 g by 18.

Exercise

1. Convert 3 kg 356 g to grams only. 2. Convert 0.84 kg to grams.

3. Convert 1 17

50 kg to grams. 4. Convert 2 045 g to kilograms only.

5. Convert 3 124 g to kilograms and grams. 6. Add 5 kg 495 g to 2 kg 705 g.

7. 1.785 kg to 0.578 kg. 8. Subtract 3 kg 715 g from 7 kg 875 g.

9. What is 5 kg 297 g from 2 kg 775 g? 10. Solve 2 kg × 5.

11. 5.35 kg × 4. 12. Divide 63 kg 720 g by 6.

13. Divide 18 kg 198 g by 9. 14. Multiply 5 kg 39 g × 8.

15. The weight of 7 crates of mineral is 10.5 kg. What is the weight of one?

WEEK 3

TOPIC: TIME

SUBTOPIC: TELLING THE TIME ON THE CLOCK

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

1. Identify the seconds, minutes, and hour on a clock

2. tell the time on a clock

3. read the calendar and recite 6o seconds make 1 minute

4. use the a.m and p.m notation for the time of the day

5. convert the unit of time

CONTENT

TIME

Telling time to hours and minutes

ToThe clock face on the left shows the hour and minutes hands.

The clock face is divided into 12 large divisions and 60 small divisions. Between 2 large divisions there are 5 small divisions. When the minute hand moves from 12 and back to 12 (one complete turn), it moved 60 minutes and the hour hand moves from one large number to another. This means that the hour-hand moves through 1 large division every 60 small divisions the minute hand moved. Thus: 60 minutes = 1 hour