1. Time
Primary 4 Mathematics

2. Chapter Learning Outcomes
Telling time in seconds
Understanding and using the 24-hour clock
Solve word problems related to time

3. Time In Seconds There are three hands on this clock.
This is the hour hand.
This is the minute hand.
This is the second hand.

4. Time In Seconds I can recall that 1 hour = 60 minutes.
Well, 1 minute = 60 seconds!
We use s to stand for seconds.
Use a stopwatch to see what you can do in 1 second!

5. Time In Seconds
3.00 p.m.
after 30 s
3.01 p.m.
after 30 s

6. What is the time shown on the clock?
The 24-hour Clock
What is the time shown on the clock?
9.30 a.m.
Nine thirty a.m.
Using 12-hour clock
09 30
Zero nine thirty hours
Using 24-hour clock

7. What is the time shown on the clock?
The 24-hour Clock
What is the time shown on the clock?
10.00 p.m.
Ten p.m.
Using 12-hour clock
22 00
Twenty-two hundred
hours
Using 24-hour clock

8. The 24-hour Clock

9. Example Fill in the blanks. 12-hour clock 24-hour clock 4.30 a.m.
17 20
3.15 p.m.
02 05
Noon
21 55
12.40 p.m.
05 05
04 30
5.20 p.m.
15 15
2.05 a.m.
12 00
9.55 p.m.
12 40
5.05 a.m.

10. I can solve this using a time line.
Word Problems
Arianne started reading the newspaper at She finished reading at How long did she take to read the newspaper?
I can solve this using a time line.
She took 1 h 20 min.

11. Count backwards on the time line.
Word Problems
Justin finished cooking his lunch at He took 2 h 10 min to cook. At what time did he start cooking his lunch?
Count backwards on the time line.
He started cooking at

12. Example
Andy took a flight from Melbourne to Singapore which lasted 9 h 30 min. He stopped in transit for 2 h before taking a connecting flight to Penang for 1 h 15 min. If he landed at on Tuesday, when did he leave Melbourne?
He left Melbourne at on Monday.

13. Example
Jermaine started watching a movie marathon at He finished watching the movies at the following day. How long was the movie marathon?
4 h 30 min + 2 h 45 min = 6 h 75 min = 7 h 15 min
The movie marathon lasted 7 h 15 min.

14. Reference - Textbooks Learning Outcomes Telling time in seconds
4B Pg 81 – 85
4B Pg 64 – 67
Understanding and using the 24-hour clock
4B Pg 86 – 89
4B Pg 68 – 71
Solve word problems related to time
4B Pg 89 – 97
4B Pg 72 – 76