Singapore Mathematics | International Edition: Time and the 24-Hour Clock

Singapore Math guide to time and the 24-hour clock for families and teachers outside Singapore. What Primary 1 to Primary 3 students learn about telling time, durations and the 24-hour clock, and how to practise at home.

Time is the one everyday measure that is not built on tens, hundreds and thousands.

There are 60 minutes in an hour and 60 seconds in a minute, and that is where most errors begin.

In Singapore Mathematics, time is taught from Primary 1 to Primary 3. Students tell the time to 5 minutes and then to the minute, use am and pm, and measure time in hours, minutes and seconds.

By Primary 3 they find a start time, finish time or duration from the other two, and use the 24-hour clock. Time does not appear as a topic in Primary 4.

This guide is useful for families and teachers who want to:

• understand what Singapore expects from Primary 1 to Primary 3;
• teach time at home in a clear sequence;
• prepare a child who is moving into a Singapore school; or
• support a student using Singapore Math materials in another country.

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What Time Means in Singapore Mathematics

Time questions ask one of two things: when something happens, or how long it lasts.

A time of day, such as 3:15 pm, answers “when”. A duration, such as 1 h 20 min, answers “how long”.

The units are linked by 60, not by 100:

• 1 hour = 60 minutes; and
• 1 minute = 60 seconds.

The 12-hour clock uses am for times after midnight and before noon, and pm for times after noon and before midnight. The 24-hour clock numbers the hours of the day from 0 to 23, so no am or pm is needed.

This guide writes times with a colon, such as 3:15 pm and 15:15. Materials differ in how they print times, so follow the format your child’s materials use.

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Where Time Sits in the Singapore Syllabus

In the current primary syllabus, time is taught from Primary 1 to Primary 3.

At Primary 1, students learn:

• telling time to 5 minutes;
• the use of “am” and “pm”;
• the abbreviations h and min; and
• the duration of one hour and half an hour.

At Primary 2, students learn:

• telling time to the minute;
• measuring time in hours and minutes; and
• converting time in hours and minutes to minutes only, and back.

At Primary 3, students learn:

• measuring time in seconds;
• finding the start time, finish time or duration, given the other two; and
• the 24-hour clock.

Level	What students do with time
Primary 1	Tell time to 5 minutes; am and pm; h and min; one hour and half an hour
Primary 2	Tell time to the minute; hours and minutes; convert to and from minutes
Primary 3	Seconds; start time, finish time and duration; the 24-hour clock

No Time topic appears in the Primary 4 content. Primary 5 Foundation Mathematics revisits time, including duration and the 24-hour clock.

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How Singapore Teaches Time

1. Read the clock face

Children learn what each hand shows. The short hand points to the hour, and the long hand shows the minutes, counted in fives at Primary 1.

2. Place the day in order

Morning, noon, afternoon, evening, midnight. Then am and pm are attached to these parts of the day.

3. Read to the minute

At Primary 2, children count in fives to the nearest mark, then count on in ones.

4. Convert hours and minutes

1 h 25 min = 60 min + 25 min = 85 min. And 140 min = 120 min + 20 min = 2 h 20 min.

5. Find durations by counting on

At Primary 3, a timeline helps. Count from the start time to the next full hour, then in whole hours, then the remaining minutes.

6. Use the 24-hour clock

For times from 1 pm to 11:59 pm, add 12 to the hour: 3:15 pm becomes 15:15. Morning times keep their hour, so 9:40 am stays 9:40, though some materials write 09:40. The hour after midnight is hour 0, so 12:15 am becomes 00:15.

The order matters. A child who learns durations as a subtraction rule often treats an hour as 100 minutes.

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Worked Examples

In both examples, the method is the same: count on to a full hour, then in hours, then the rest.

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Common Mistakes

• Treating an hour as 100 minutes. A child finds 1:20 − 10:45 by column subtraction. Fix: count on along a timeline, using 60 minutes in an hour.
• Converting by joining digits. A child writes 2 h 15 min as 215 min. Fix: 2 h = 120 min, so 2 h 15 min = 135 min.
• Misreading the hour hand. At 2:50 the hour hand is nearly at 3, so a child reads 3:50. Fix: the hour is the number the short hand has passed.
• Mixing am and pm across noon. A child says 10:45 am to 1:20 pm is under an hour. Fix: mark noon on the timeline before counting.
• Adding 12 to the wrong times. A child writes 9:40 am as 21:40, or 12:30 pm as 24:30. Fix: add 12 only from 1 pm onwards. 12:30 pm is 12:30 on the 24-hour clock.
• Confusing a time and a duration. A child answers “1:20” when the question asks how long. Fix: underline “when” or “how long” in the question.

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Teaching Time Outside Singapore

Time is taught everywhere, but formats and timing differ. A few points are worth knowing.

• Formats. Materials differ in how they print 12-hour and 24-hour times. Follow your child’s materials and show other formats as alternatives.
• Abbreviations. Singapore’s Primary 1 content uses h and min. Encourage durations such as 1 h 25 min rather than 1.25.
• Timing. In Singapore’s current syllabus, time is taught from Primary 1 to Primary 3. Decide by readiness rather than age. The Singapore Math Grade Levels guide explains why direct conversions are unreliable.
• Speed comes later. Durations prepare for speed, but speed is not in the current primary syllabus. It is taught in Secondary 1, in Rate and Speed.
• Analogue and digital. Practise with both kinds of clock. Reading an analogue clock is the harder skill.

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How to Practise Time at Home

A short, regular routine works better than one long weekend session.

1. Ask the time on an analogue clock at two fixed points in the day.
2. Say whether each time is am or pm, and why.
3. Convert one duration between hours and minutes and minutes only.
4. Time a short task in seconds.
5. Use a real timetable or schedule to find one duration by counting on.
6. Once a week, change three times between the 12-hour and 24-hour clock.

Ten to fifteen minutes is enough when the work is focused.

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Try These

1. Write 2 h 15 min in minutes.
2. Write 200 min in hours and minutes.
3. Write 4:35 pm on the 24-hour clock.
4. A film starts at 18:50 and ends at 21:05. How long is the film?

Answers

1. 135 min. 2 h = 120 min, and 120 + 15 = 135.
2. 3 h 20 min. 180 min = 3 h, and 200 − 180 = 20.
3. 16:35. For pm times from 1 pm onwards, add 12 to the hour: 4 + 12 = 16.
4. 2 h 15 min. 18:50 to 19:00 is 10 min, 19:00 to 21:00 is 2 h, and 21:00 to 21:05 is 5 min.

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What Comes Next

Time links to several later topics.

• In Primary 5, Rate uses amounts per minute or per hour.
• In Secondary 1, Rate and Speed introduces average speed, using distance and time.
• In secondary school, Distance-Time and Speed-Time Graphs are among the real-world contexts students interpret.

A child who counts on confidently across the hour usually finds these later topics easier.

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Frequently Asked Questions

When do Singapore students learn time?

From Primary 1 to Primary 3. Primary 1 tells time to 5 minutes, Primary 2 to the minute, and Primary 3 adds seconds, durations and the 24-hour clock.

When is the 24-hour clock taught?

In Primary 3.

Is time taught in Primary 4?

No Time topic appears in the Primary 4 content. Primary 5 Foundation Mathematics revisits time, including the 24-hour clock.

When do Singapore students learn speed?

Speed is not in the current primary syllabus. Average speed is taught in Secondary 1 under Rate and Speed.

Is 12 pm noon or midnight?

12 pm is noon. Writing “12 noon” and “12 midnight” avoids confusion.

What is the best way to find a duration?

Count on: from the start time to the next full hour, then in whole hours, then the remaining minutes. A timeline makes this visible.

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Helpful Reading

• Singapore Mathematics | International Edition: Money
• Singapore Mathematics | International Edition: Length, Mass and Volume
• Singapore Mathematics | International Edition: Rate and Speed
• Primary Mathematics: Time, Money and Schedules | Worked Learning Guide
• Real-World Mathematics: Timekeeping, Clocks, Calendars, Drift and Modular Arithmetic
• Why Unit Conversion Mistakes Happen in Mathematics
• MOE Primary Mathematics Syllabus

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Time in Singapore Mathematics

Sixty, not a hundred.

When, or how long?

Count on to the hour.

Add 12 from 1 pm.

Taught this way, time stops being a set of clock tricks.

It becomes a number line that a child can walk along.

That habit carries a student from Primary 1 into rate, speed and graphs.

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Ask Bukit Timah Tutor

Bukit Timah Tutor teaches Mathematics in small groups of three students in Singapore.

If your child is learning Singapore Mathematics at home, in an international school or in a Singapore school, and you are unsure where to begin with this topic, send us a short message with the student’s level and one example of the work.

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Singapore Mathematics | International Edition is a Bukit Timah Tutor guide series for families and teachers outside Singapore. It is not a textbook and is not affiliated with MOE, SEAB or any publisher. Syllabus details were checked against MOE and SEAB documents in October 2026. Always confirm current requirements with your school.

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