What are the 12-hour and 24-hour clock?
Contents
What are the 12- and 24- hour clock?
Examples of 12- and 24- hour times
When do children learn the 12- and 24- hour clock?
Short 12- and 24- hour clock quiz
What are the 12-hour and 24-hour clock?
There are two ways of telling the time:
The 12-hour clock runs from 1am to 12 noon and then from 1pm to 12 midnight.
The 24-hour clock uses the numbers 00:00 to 23:59 (midnight is 00:00).
Examples of 12- and 24- hour times
| 12-hour clock | 24-hour clock |
| 1am | 01.00 |
| 2am | 02.00 |
| 3am | 03.00 |
| 4am | 04.00 |
| 5am | 05.00 |
| 6am | 06.00 |
| 7am | 07.00 |
| 8am | 08.00 |
| 9am | 09.00 |
| 10am | 10.00 |
| 11am | 11.00 |
| 12 noon | 12.00 |
| 1pm | 13.00 |
| 2pm | 14.00 |
| 3pm | 15.00 |
| 4pm | 16.00 |
| 5pm | 17.00 |
| 6pm | 18.00 |
| 7pm | 19.00 |
| 8pm | 20.00 |
| 9pm | 21.00 |
| 10pm | 22.00 |
| 11pm | 23.00 |
| 12 midnight | 24.00 |
When do children learn the 12- and 24- hour clock?
Children in Year 1 learn to tell the time on a 12-hour analogue clock which looks like this:
At this point, they learn to tell the time to the hour and half hour.
In Year 2 they learn that there are 24 hours in a day, 60 minutes in an hour, and 30 minutes in half an hour. They move onto reading the time to the quarter hour and then the nearest five minutes. They also start to learn about time intervals (working out the length of time between two times).
In Year 3, children learn that there are 60 seconds in a minute. They continue to tell the time with increasing speed and accuracy. Here is an example of a time interval word problem involving the 12-hour clock that they might come across:
I put some lamb in the oven at 10.30 in the morning. I take it out at 11.20 the same morning. How long has it been in the oven?
In Year 4, children need to convert between units of time (hour and minutes). They need to read, write and convert time between analogue and digital 12-hour and 24-hour clocks.
In Years 5 and 6, children are asked to solve problems involving converting between units of time. A Year 5 or 6 child might come across a problem like the following, that requires them to work out a time interval using their knowledge of both the 12-hour and 24-hour clock:
I get the 13:46 train to Manchester, which takes exactly three hours and five minutes. How many minutes before 5pm do I arrive in Manchester?
If a child were struggling with this, they might be encouraged to draw a number line in order to count forward the 3 hours and 5 minutes:
They could then convert the 24-hour clock time to 12-hour time, which would be 4:51pm. They should then be able to work out that they would arrive in Manchester 9 minutes before 5pm.
Test your knowledge: quick quiz
12- hour clock questions
Question 1: If the clock shows 9 o'clock, is it morning or evening?
Question 2: What time does the clock show if the hour hand is on the 4 and the minute hand is on the 12?
Question 3: If the clock shows 2:30 PM, how many hours until it's 6:30 PM?
Question 4: If the clock shows 7 am, how many hours until it's noon (12 pm)?
24- hour clock questions
Question 5: If the clock shows 14:00, what time is it in the 12-hour clock format?
Question 6: What time does the clock show if it says 08:30?
Question 7: If it's 19:45, what time will it be in 15 minutes?
Answers
Answer 1: It is morning.
Answer 2: 4 o'clock
Answer 3: 4 hours
Answer 4: 5 hours
Answer 5: 2 pm
Answer 6: 8:30 am
Answer 7: 20:00
