Lesson Notes By Weeks and Term - Primary 4

WEEK 3

SUBJECT: MATHEMATICS

CLASS: PRIMARY 4

TERM: 3RD TERM

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

The short form of hour is h and the short form of minutes is min.

Examples:

Exs: 

EXERCISE

Draw a clock to show each of the following times

1. 8:15. 2. 4:18. 3. 3:45.       4. 1:20.     5. Twenty- five minutes to seven      6.  Thirteen minutes past six

USING THE A.M AND P.M NOTATION FOR THE TIME.

In English system the day starts at midnight and ends at the next midnight.

The day begins just after 12 o’clock at midnight. The next 12 o’clock in the day time is called midday. Then the next 12 o’clock is the next midnight.

The time from a midnight to coming midday is called antemeridian. It is written in short as a.m. We say the time between midnight and noon is called a.m.

The time between 12 o’clock of the day, i.e., midday to next midnight is known as postmeridian. It is written in short as p.m.

We say the time between midday (noon) to next midnight is called p.m.

Antemeridian (a.m.) and Postmeridian (p.m.) are Latin words which mean midnight to noon (a.m.) and noon to midnight (p.m.). We use a.m. to express the time between 12:00 midnight and 12:00 noon. We use p.m. to express the time between 12:00 noon and 12:00 midnight. 

Our general clock expresses the time of both time periods by the same numbers. We affix a.m. for the time between midnight and noon and p.m. for the time between noon and midnight.

To be bed at 10 p.m. in the night and get up at 6 a.m. in the morning.

The time before 12:00 noon is expressed as a.m. and the time after 12:00 noon is expressed as p.m. When it is 12 0'clock at night, we say it is 12:00 midnight or 00:00 hour. When it is 12 o'clock during day, we say it is 12:00 noon or 12:00 hours.

Examples:

• Twenty minutes past ten in the morning is written as 10: 20
• Half past three in the afternoon is written as 3:30pm

Exercise

À. Write out these times using a.m or p.m

• The time is when the school assembly begins at 7:30
• The time when the school closes at 2:0clock
• The time when you have your dinner at 7 O'Clock
• The time when you go to bed at 9 o'clock.

B. Copy and complete the following statements. The first is done for you

• Four hours after midnight is 4 a.m
• Three hours before midnight is...................
• Nine hours after midnight is................
• Five hours after midday is....................
• Eleven hours after midday is.... ..........

CONVERSION OF UNIT OF TIME

Examples:

1. Convert 310 seconds to minutes and seconds

Solution:

60 seconds = 1 minutes

310 seconds =310÷60 minutes

                   = 310/60

                   = 5 minutes 1 seconds

2. Convert 16 mins 43 seconds

Solution:.

60seconds = 1 minutes

16 minutes= 16× 60 seconds

                = 160×6s

               =960s

16mins 43s= 960s+43s

                = 1003 seconds

...Consider the following examples on units of time:

1. Convert the following:

(i) 7 days 6 hours into hours.

(ii) 6 hours 40 minutes into minutes.

(iii) 4 minutes 25 seconds into seconds.

Solution:  

(i) 1 day = 24 hours

Therefore, 7 days 6 hours    = (7 x 24) hours + 6 hours

                                      = 168 hours + 6 hours

                                      = 174 hours

(ii) 1 hour = 60 minutes

Therefore, 6 hours + 40 minutes    = (6 x 60) minutes + 40 minutes

                                                   = (360 + 40) minutes

                                                  = 400 minutes

(iii) 1 minute = 60 seconds 

Therefore, 4 minutes 25 seconds   = (4 x 60) seconds + 25 seconds

                                                  = (240 + 25) seconds

                                                  = 265 seconds

Exercise

1. Convert each of the following to seconds

6mins

10mins

12mins

2mins 8s

2. Convert each of the following to minutes

360s

1080s

1800s

1020s