#### Lessons

In this lesson, we will learn:

• 24-hour clock time is used instead of 12-hour clock time to avoid being confused about AM or PM
• There are 24 hours in a day, so instead of the hours being labelled 1-12 AM or 1-12 PM, we can label them from 1-24 instead.
• There are rules for converting between 12-hour clock time and 24-hour clock time (and vice versa)

Notes:

• Using 12-hour clock time can be confusing because you might not know if someone is telling you a time for AM or PM (ex. is it 6 o’clock in the morning or evening?)

• By using 24-hour clock time, we can avoid the confusion of not knowing AM/PM
• There are 24 hours in a day
• The previous days ends, and the new day starts at midnight (12:00 AM)
• The middle of the day is right at noon (12:00 PM)
• For 24-hour time, you say the hours directly from 00 until 24 (or back to 00)

• This table shows all the equivalent times for the 12-hour clock and 24-hour clock:

• When it goes to midnight (12AM), it becomes 24:00 which is the same as 00:00
• Do not use this table when doing the practice questions; only for checking

• To convert from AM/PM time (12-hour clock time) to 24-hour time:

• $\qquad$ 1. Minutes: stay the same
$\qquad$ 2. Hours:

$\qquad$ 3. Exceptions: 12AM = 00h, 12PM = 12h
• Ex. (8:46AM = 08:46), (5:13PM = 17:13), (12:07AM = 00:07)

• To convert from 24-hour time to AM/PM time :

• $\qquad$ 4. Minutes: stay the same
$\qquad$ 5. Hours
• if < 12, keep same, remove leading 0, and write AM
• if > 12 subtract 12 and write PM

$\qquad$ 6. Exceptions: 00:00 = 12AM and 12:00 = 12PM
• Ex. (09:54 = 9:54AM), (22:38 = 10:38PM), (00:16 = 12:16AM)
• Introduction
Introduction to Reading 24-Hour Clock Time:
a)
What is 24-hour clock time?

b)
Equivalent 24-hour times on the analog clock

c)
Comparing 12-hour times and 24-hour times in a table

d)
How to convert between 12-hour clock time (AM/PM) and 24-hour clock time

• 1.
Converting AM/PM Time into 24-Hour Time
Write as 24-hour time instead of AM/PM time.
a)
9:56 AM

b)
6:18 AM

c)
1:35 PM

d)
4:27 PM

e)
12:01 AM

• 2.
Converting 24-Hour Time into AM/PM Time
Write as AM/PM time instead of 24-hour time.
a)
05:40

b)
22:23

c)
18:05

d)
11:37

e)
00:51

• 3.
Noon and Midnight are Special Exceptions for 24-Hour Time
a)
How do you write noon and midnight in AM/PM time?

b)
How do you write noon and midnight in 24-hour time?

c)
What is the rule for all other time conversion (not noon or midnight) for AM and PM hours into 24-hour time?

• 4.
24-Hour Time - True False Questions
Read the descriptions of the time shown below. Write true (T) or false (F) for each description.

19:45