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Convert between times given in 12 and 24 hours
I can convert between times given in 12 and 24 hours.
Lesson 2 of 5
New
New
- Year 4
Convert between times given in 12 and 24 hours
I can convert between times given in 12 and 24 hours.
Lesson details
Key learning points
- There are 24 hours in a day
- Times after midday can be written as pm
- Times after midday can be written in the 24 hour clock by adding on 12 hours
Keywords
Am - The hours between midnight and midday.
Pm - The hours between midday and midnight.
24 hour clock - A way of expressing the time using the numbers 0-23 for the hours.
Common misconception
It is tempting to say that we need to add 12 hours to any pm times to turn them into 24 hour times. However, it is a slight over-generalisation and does not apply to 12:00 pm up to 12:59 pm.
A teaching point is made of this and opportunities to apply the knowledge are given in the Practice tasks. It is worth really focusing on this as it comes up and paying attention to it while pupils are engaged with the Practice tasks.
Some pupils may need scaffolding, particularly if they need support with the arithmetic of adding 12. A double number line, with the 12 hour times on the top (with am and pm) and the 24 hour times on the bottom will help to support their thinking. As with all scaffolding, remove as soon as possible.
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.9 + 12 =
9 + 12 =
Q2.23 − 12 =
23 − 12 =
Q3.True or false. am means the hours between midday and midnight.
True or false. am means the hours between midday and midnight.
True
Q4.Which part of this 12 hour digital clock shows the hours?
Which part of this 12 hour digital clock shows the hours?
b
c
Q5.Match the analogue times to the correct digital times.
Match the analogue times to the correct digital times.
Q6.This is a 24 hour digital clock. Which numbers could be displayed on the part marked a?
This is a 24 hour digital clock. Which numbers could be displayed on the part marked a?
00 to 60
01 to 60
01 to 59
Assessment exit quiz
6 Questions
Q1.What is 12:00 pm in 24 hour digital time?
What is 12:00 pm in 24 hour digital time?
00:00
Q2.Match the 12 hour digital times to the correct 24 hour digital times.
Match the 12 hour digital times to the correct 24 hour digital times.
Q3.Match the 12 hour digital times to the correct 24 hour digital times.
Match the 12 hour digital times to the correct 24 hour digital times.
Q4.Order these times from earliest to latest within one day.
Order these times from earliest to latest within one day.
Q5.7:00 pm in 24 hour time is :00
7:00 pm in 24 hour time is :00
Q6.What is 21:00 in 12 hour time? :00 pm
What is 21:00 in 12 hour time? :00 pm
