Convert between times given in 12 and 24 hours | Maths

Starter quiz

9 + 12 = ______
- '21' ✓
23 − 12 = ______
- '11' ✓
True or false. am means the hours between midday and midnight.
- True
- False ✓
Which part of this 12 hour digital clock shows the hours?
- a ✓
- b
- c
Match the analogue times to the correct digital times.
- 3 o'clock in the morning
  
  ⇔
  
  3:00 am ✓
- midday
  
  ⇔
  
  12:00 pm ✓
- 4 o'clock in the morning
  
  ⇔
  
  4:00 am ✓
- 10 o'clock at night
  
  ⇔
  
  22:00 ✓
This is a 24 hour digital clock. Which numbers could be displayed on the part marked a?
- 00 to 60
- 01 to 60
- 00 to 59 ✓
- 01 to 59

Exit quiz

What is 12:00 pm in 24 hour digital time?
- 12:00 ✓
- 00:00
Match the 12 hour digital times to the correct 24 hour digital times.
- 11:00 am
  
  ⇔
  
  11:00 ✓
- 12:00 pm
  
  ⇔
  
  12:00 ✓
- 11:00 pm
  
  ⇔
  
  23:00 ✓
Match the 12 hour digital times to the correct 24 hour digital times.
- 5:30 pm
  
  ⇔
  
  17:30 ✓
- 7:30 pm
  
  ⇔
  
  19:30 ✓
- 9:30 pm
  
  ⇔
  
  21:30 ✓
Order these times from earliest to latest within one day.
- 1
  
  ⇔
  
  11:00
- 2
  
  ⇔
  
  12:00 pm
- 3
  
  ⇔
  
  1:00 pm
- 4
  
  ⇔
  
  14:00
7:00 pm in 24 hour time is ______:00
- '19' ✓
What is 21:00 in 12 hour time? ______:00 pm
- '9' ✓

Worksheet

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Presentation

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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

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.

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.