Reading 24-hour clock time

Reading 24-hour clock time

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)
Time: Reading 24-Hour Clock Time

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

    • 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:
      • if AM, keep the same (add leading 0)
      • if PM add 12

    \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
    Answer the questions about special times in the day.
    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

    Time: Reading 24-Hour Clock Time