1. 24 Hour Clock
Grade 6 Math

2. Midnight – Midday There are 24 hours in a day!
The first 12 hours of the day are from:
Midnight – Midday

3. Think, Pair, Share
What places use a 24 hour clock?

4. In 12 hour time We count from midnight to midday
Then we count from midday to midnight!

5. Count the hours in the day…

6. In 24 hour time we count from...
1 to 24!
1,2,3,4,5,6,7,8,9,10,11,12,
13,14,15,16,17,18,19,20,21,22,23,24!

7. We don’t use AM or PM in 24 hour clock!
12 noon
01:00
02:00
03:00
04:00
05:00
06:00
07:00
08:00
09:00
10:00
11:00
12:00

8. For PM times we keep counting to 24!
12 midnight
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
24:00 / 00:00

9. Look at Midnight!
12:00 midnight
00:00
Why???

10. It’s a new day
Midnight is the very beginning of the new day.
We have counted a full 24 hours
The day is over – so we start counting again from zero!
1,2,3,4,5,6,7,8,9,10,11,12, ,14,15,16,17,18,19,20,21,22,23,24!

11. What about the minutes? In 24 hour time the minutes don’t change.
1.15am :15
2:45am :45
6:24pm :24
8:30pm :30
10:45am :45
11:35pm :35

12. Noon & Midnight Noon Midnight 12:00pm 12:00 12:15pm 12:15
12:00am 00:00
12:15am 00:15
12:30am 00:30
12:45am 00:45
12:50am 00:50
12:05am 00:05
12:10am 00:10

13. Telling Time... If it’s 10:00PM, what time is it on the 24 hour clock?
If it’s 19:00 what time is it on the 12 hour clock?

14. Telling Time up to the Second
We use a similar method when telling time up to the second.
For example, on a 24 hour clock, 10:18:28 means that 18 minutes and 28 seconds is after 10 a.m.
How many second have passed after 6 p.m.?
6:42:06