What Is The 12-Hour And 24-Hour Clock? Explained for Primary School Parents

This article summarises what primary school pupils in KS1 and KS2 will be taught about the 12-hour clock and 24-hour clock and provides some telling the time questions for children to practise telling digital and analogue time on digital and analogue clocks. 

What is the 12-hour clock?

The 12-hour clock is most commonly represented on an analogue clock with the numbers 1-12; when shown on a digital clock, it is usually accompanied by a.m. (‘ante meridiem’ – Latin for ‘before midday’) or p.m. (‘post meridiem’ – Latin for ‘after midday’).

What is the 24-hour clock?

The 24-hour clock is more often shown on digital clocks and is written in a 4-digit form, with the first two digits representing the hour and the last two representing the minutes.

There is no need for a.m. or p.m. as each time represents each hour in a 24-hour day. For example, 0300 = 3rd hour of the day, or 3am; 1400 = 14th hour of the day, or 2pm; 1830 = 30 minutes past the 18th hour of the day, or 6.30pm.

How to convert from a 12-hour clock to a 24-hour clock?

To convert from a 12-hour clock to a 24-hour clock, children may be taught to add 12 to the hours after midday, e.g. 3pm becomes 15:00 because 3 + 12 = 15.

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
12pm	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
12am	00:00

When will my child learn about the 12-hour and 24-hour clock in primary school?

12 hour and 24 hour clock in KS1

In KS1 pupils will learn to tell the time to the hour and half past the hour and draw the hands on a clock face to show these times (Year 1) and tell and write the time to five minutes, including quarter past/to the hour and draw the hands on a clock face to show these times (Year 2).

12 hour and 24 hour clock in KS2

Children’s learning of time is continued into lower KS2, where they will tell and write the time from an analogue clock, including using Roman numerals from I to XII, and 12-hour and 24-hour clocks (Year 3).

The National Curriculum’s non-statutory guidance also advises that pupils use both analogue and digital 12-hour clocks and record their times. In this way they become fluent in and prepared for using digital 24-hour clocks in year 4, where they will then learn to read, write and convert time between analogue and digital 12- and 24-hour clocks.

There are no specific objectives about time in upper KS2.

How do the 12- and 24-hour clock relate to other areas of maths?

Children are sometimes required to read and interpret timetables (such as timings of a school day, or a bus timetable) which will often use timings either written in the 12- or 24-hour clock.

12 hour clock & 24 hour clock worksheet questions

1. What time does this clock show?

(Answer: 8:30)

2. Lily says, ‘On my clock face, the big hand is on the 4 and the little hand is between the 8 and the 9’. What is the time on Lily’s clock face?

(Answer: 20 past 8)

3. Toby went to cubs at 7pm. He finished one hour later. What time did he finish? Give your answer using digital 24-hour clock time.

(Answer: 2000h)

4. These are all times on the same morning.
A: 7:56 am
B: quarter to eight
C: six minutes to eight
D: half past seven
Write the letters for the times in order, starting with the earliest.

(Answer: D, B, C, A)

5. A clock shows this time twice a day.

Tick the two digital clocks that show this time:
A: 03:45
B: 02:45
C: 09:45
D: 21:45
E: 14:45

(Answer: B and E)

If your child is struggling then this article on telling the time breaks down step by step a foolproof method for teaching time at KS1 and KS2.