Topic 5 (Time)-Y4 09.ppt

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Murugiah Velayutham/TCG 1

Teaching of Mathematicsfor Year 4 Primary School

TOPIC 5 : TIME

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TOPIC 5 TIME

Year 4 syllabus:1. Reading & writing time.

In hours & minutes according to the 12-hours system.

eg. 8.30am ,9:15pmHalf past eight in the morningEight thirty in the morning

Nine fifteen in the evening A quarter past nine in the evening:

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Year 4 syllabus2. Time Schedule

Construct, read and extractinformation from a simple schedule.

Extract information from a calendar.

Days in a given monthWeeks in a given year

Holiday, festivals in a given month.

- Solve simple real life problemsinvolving reading calendar

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Year 4 syllabus

3. Relationship between units of TimeState relationship between units of time:1 day = 24 hours, 1 year = 365/366 days1 decade = 10 yearsConvert:Years to days, to months vice versa.Decades to years vice versaDays to hours vice versaHours to minutes Vice versa.

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Year 4 syllabus

4. Basic operations involving Time

- Add, subtract, multiply and divide timeinvolving conversion of units with answersin compound units of:

a) hours & minutesb) years & months

c) decades & years

- Solve problems involving basic

operations of time.

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Time is an abstract concept- Time is measured using a mixture ofbase 12 and base 60 systems and when

extended to days, months and years, ituses base 4, 7, 365 and 28, 29, 30 and31 systems

- Time is measured indirectly

- Clocks comes in all sorts of styles anddesigns

Difficulties in Teaching Time

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Pedagogical Content Knowledge

Leap year:

The number of days in a year depend onwhether it is a common or a leap year.

If a year can be divided by 4 and not a multiple of

100, then the year is a leap year.If the year can be divided by 4 but is a multiple of100, then it is not a leap year.

If a year is a multiple of 100 and can be divided by

400, then it is a leap year.Which of the following are leap year?

1000, 1004, 1014, 1600, 1900, 2000, 2008

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Reading & Writing Time

Activity 1:

Ask students to read and write the timeshown below:

1:15 in the afternoon.

1:15 pm

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Reading & Writing Time

Activity 2:

Write the following time:(a) Twenty five minutes past nine in the

morning.

9:25 am(b) Half past three in the afternoon.

3:30 pm

(c) Ten minutes to eight in the evening

7:50 pm

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Reading & Writing time

Activity 3:

Draw the correct hour and minute inthe picture provided:

(a) A quarter past five inthe morning

(b) Half past three in the afternoon

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Time ScheduleExtract information from a calendar

January = 31 days July = 31 daysFebruary = 28 days August = 31 days

March = 31 days September = 30 days

April = 30 days October = 31 daysMay = 31 days November = 30 days

June = 30 days December = 31 days

365 days= 1 year ( non leap year)366 days= 1 year ( leap year)

1 decade= 10 years

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Relationship between Units of Time(1) Convert Years to Days

(a) Non- leap yearConvert 3 years to days

3 x 365 = 1095 days

(b) Leap YearConvert 3 years including a leapyear

(2 x 365) + 366 = 1096 days

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Relationship between Units of Time(2) Days to years

Convert 1460 days to years

1 4 6 0- 3 6 5 1 year1 0 9 5

- 3 6 5 1 year7 3 0

- 3 6 5 1 year3 6 5

- 3 6 5 1 year0 0 0 4 years

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Relationship between Units of Time(3) Decade to years

Portuguese conquered Malacca 50decades ago. How many years have passedsince then?

(50 x 10) = 500 years

(4) Years to decadeTuanku Abdul Rahman was born in 1903.How many decades have past since thenuntil now?

2009 1903 = 106 years106 years = decade???106 10 = 10 decades 6 years

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7.3 Relationship between Units of

Time

(5) Years to monthsConvert a year to months

( x 12) = 6 months

(6) Months to years

Convert 148 months to years148 12 = 12 years 4 months

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7.3 Relationship between Units of Time

(7) Days to Hours

Danny spends one third of the day inschool. How many hours does hespends in school?

(1/3 x 24) = 8 hours(8) Hours to days

Convert 360 hours to days

360 24 = 15 days

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Relationship between Units of Time

(9) Hours to minutes

Dollah spends 5 hours 30 minutes tocomplete his assignment. How manyminutes will that be?

(5 x 60) + 30 = 300 +30 = 330 minutes(10) Minutes to hours

Convert 690 minutes to hours

690 60 = 11 hours 30 minutes

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Basic Operations :Addition &Subtraction involving Time

(1) Addition of time(a) What time is 15 hours after

10:00 am??15 hours + 10 hours = 25 hours

25 hours 12 hours = 13 hours(change a.m to p.m)13 : 00 p.m

13 hours 12 hours = 1 hour(change p.m to a.m)1:00 am

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Addition & Subtraction involving

Time

(1) Addition of time(b) 35 minutes + 55 minutes

=_______ hours _______ minutes

35 minutes

+55 minutes

90 minutes90 60 = 1 hour 30 minutes

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Addition & Subtraction involving Time

(1) Addition of time (years & months)

(c) 25 months + 48 months=_______ years _______ months

25 months

+48 months

73 months73 12 = 6 years 1 month

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Time

(1) Addition of time (years & decades)(d) 40 years + 21 years

=_____ decades ____ years

40 years

+21 years

61 years61 10 = 6 decades 1 year

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Time

(2) Subtraction of time (weeks & days)(a) What is four weeks one day minus

two weeks six days?

Weeks Days

3 4 1+7

- 2 61 2

Answer: 1 week 2 days

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Time

(2) Subtraction of time (days & hours)(b) What is four days eleven hours

minus two days seventeen hours?

Days Hours

3 4 11+24

- 2 171 18

Answer: 1 day 18 hours

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Time

(2) Subtraction of time (hours & minutes)(c) What is four hours eleven minutes

minus two hours forty seven minutes?

Hours Minutes

3 4 11+60

- 2 471 24

Answer: 1 hour 24 minutes

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Time

(2) Subtraction of time (minutes & seconds)(d) What is four minutes eleven seconds

minus two minutes forty seven seconds?

Minutes Seconds3 4 11+60

- 2 471 24

Answer: 1 minute 24 seconds

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Multiplication & Division involving Time

(1) Multiplication involving time (seconds &

minutes)(a) 48 seconds X 2 =______

Solution: 4 8

x 29 6 seconds

96 seconds: 96 60

= 1 minute 36 seconds

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(1) Multiplication involving time (years &

months)(b) 15 months X 5 =______

Solution: 1 5

x 57 5 months

75months: 75 12

= 6 years 3 months

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(1) Multiplication involving time (years &

decades)(c) 18 years X 7 =______

Solution: 1 8

x 71 2 6 years

126years: 126 10

= 12 decades 6 years

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(2) Division involving time (hours & minutes)

(a) 150 minutes 2 = ___hour ___ minSolution: 1 5 0 2

= 75 minutes

75 minutes = 75 60

= 1 hour 15 minutes

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Multiplication & Division involving

Time

(2) Division involving time (years & months)(b) 128 months 8 = ___years ___ months

Solution: 1 2 8 8= 16 months

16 months = 16 12

= 1 year 4 months

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Multiplication & Division involving

Time

(2) Division involving time (years & decades)(c) 114 years 6 = ___decade ___ years

Solution: 1 1 4 6= 19 years

19 years = 19 10

= 1 decade 9 years

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Solving Problems involving Time

Problems involving time usually involveoperations of addition, subtraction,multiplication and division.

We have to change the amount of timeinto the same units in order to solve

problems involving more than oneoperations.

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Example:

Hanifah stopped at Ellas restaurant forlunch. He stayed there for three and ahalf hours until he had to leave to meethis friend, Wahab, at the bus station.

The bus station is a 20- minute walk fromEllas restaurant. What is the total timein minutes taken by Hanifah by the timehe met his friend?

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Solution Strategy:

(i) What information is given?

Stayed at restaurant: 3 hours 30 minutesTime spent to walk: 20 minutes

(ii) What is asked for?

Total time taken

(iii) What operations are needed?

Multiplication & addition

(iv) Solution:

3 hours 30 min = (3 x 60) + 30 = 210 minSpent walking = 20 min

Total = 210 + 20 = 230 minutes.

Topic 5 (Time)-Y4 09.ppt

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