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We can change 12 hour clock am or pm times into 24 clock times and vice versa.
We can work out the time intervals between two times in either the 12 or 24 hour clock
Year 5 Unit 16
What we are learning:
- Once children can tell the time reliably using the 12 hour clock, and understand the difference between 9.30am and 9.30pm etc they can learn about the 24 hour clock as well
- We need to recognise the way we write both 12 hour clock times and 24 hour clock times
- 12 hour clock times always need am or pm after them to show whether they are before or after midday, (12 noon).
- 24 hour clock times with a single digit hour often have a zero place holder in them, e.g. 8.30 am is written as 08:30
- 24 hour clock times don’t have am or pm after them because we keep counting on from 12 noon. 1.00pm is therefore written as 13:00, 2.00pm is written as 14:00 and so on until we get to midnight. We use a colon (:) between the hours and minutes.
- 12 midnight in the 12 hour clock is 00:00 in the 24 hour clock.
ACTIVITY 1: CONVERTING CLOCK TIMES MENTALLY
Activities you can do at home:
Talk about the time of day and times when you will be doing things. Try to convert these times to 24 hour clock as well for a game. Ask, what time will we be having supper tonight? How would you say this in 24 hour clock?
Work out the differences between two times using real life situations, e.g.
– How long do you spend at school each day?
– How long is this film?
– If I start cooking supper at 6.10pm and it will take 45 minutes, what time will it be ready?
Good questions to ask:
Where do we see the time written in the 12 hour clock?
Where is it written in the 24 hour clock?
What is the same, or nearly the same about them?
What is different about them?
Which do you like to use?
What makes you want to use this form of recording time?
If your child:
Confuses 12 and 24 hour clock times
Draw a number line to show that the 12 hour clock goes from 12 midnight to 12 midday and then on to 12 midnight again, but in the 24 hour clock we keep counting on from midday each hour.