Home›11+›Maths›Measurement (space and time)›Time, calendars and timetables
Time, calendars and timetables
12-hour and 24-hour clocks, bus and train timetables, time zones and leap years.
Video coming soon
The written summary and downloads below are complete and ready to use.
Time is everywhere: the start of school, the bus home, a film, a flight, a birthday. In this lesson you will learn how to:
- read a clock and change between seconds, minutes, hours, days, weeks and years
- use the 12-hour clock (am and pm) and the 24-hour clock
- work out how long something takes, and when it starts or ends
- read bus and train timetables
- work with time zones around the world
- use a calendar and spot a leap year
Dark blue: whole numbers
Red dot: the decimal point
Blue: digits after the point
1. Reading a clock, and the units of time
Key idea
A clock has two hands. The short hand shows the hour. The long hand shows the
minutes: each number is 5 minutes, so the 3 means 15 minutes and the 9 means 45 minutes. On the
right-hand side we say past the hour. On the left-hand side we say to the next hour.
Past and to
From the 12 round to the 6 is past: 10 past, quarter past, half past. From the 6 round to the 12 is to: twenty to, quarter to, five to.
Example 1: what time does this clock show?
- The long hand is on the 9. Count in 5s:9 × 5 = 45 minutes
- The short hand is between the 3 and the 4. It has not reached the 4 yet, so the hour is still:3
Answer3:45, or quarter to 4.
| 60 seconds | = | 1 minute |
| 60 minutes | = | 1 hour |
| 24 hours | = | 1 day |
| 7 days | = | 1 week |
| 14 days | = | 1 fortnight (2 weeks) |
| 12 months | = | 1 year |
| 365 days | = | 1 year (366 days in a leap year) |
| 10 years | = | 1 decade |
| 100 years | = | 1 century |
Example 2: how many minutes is 2 hours 15 minutes?
- Each hour is 60 minutes:2 × 60 = 120
- Add the 15 minutes:120 + 15 = 135
Answer135 minutes
Example 3: write 200 seconds in minutes and seconds
- Count in 60s as far as you can go:60, 120, 180: that is 3 minutes
- The seconds left over:200 − 180 = 20
Answer3 minutes 20 seconds
Watch out
Time does not work like decimals. There are 60 minutes in an hour, not 100. So 1.5 hours is
1 hour 30 minutes, not 1 hour 50 minutes.
Set the clock
How to play
- Drag the long hand round to change the minutes, and the short hand to change the hour. Watch the short hand creep on as the minutes go by. (Keys: left and right arrows move the minutes, up and down move the hour.) Then press Check.
- Two with no slips moves you up a level. Level 1 has o’clock, half past and quarter times, level 2 every five minutes, and level 3 any minute on the 24-hour clock, with am or pm to choose.
2. The 12-hour and 24-hour clock
Key idea
A clock face goes round twice a day, so the 12-hour clock adds am (from midnight to
noon) or pm (from noon to midnight). The 24-hour clock keeps counting after noon: 1 pm is 13:00,
2 pm is 14:00. It always uses four digits, so 9:05 am is written 09:05.
One whole day
Example 1: write 7:45 pm in 24-hour time
- It is pm, so add 12 to the hour:7 + 12 = 19
Answer19:45
Example 2: write 15:20 in 12-hour time
- The hour is more than 12, so take away 12:15 − 12 = 3
Answer3:20 pm
Example 3: midnight and noon
- 12:30 am is half an hour after midnight. The 24-hour clock starts again at 00:00:30
- 12:30 pm is half an hour after noon. Do not add 12:12:30
Answer12:30 am = 00:30 and 12:30 pm = 12:30
Watch out
Only add 12 for pm times from 1 pm onwards. Times from noon to 12:59 pm stay as 12, and times from midnight to
12:59 am start with 00. Midnight itself is 00:00.
The day ribbon
How to play
- Drag the red marker along the day (or use the arrow keys) to the time asked for, and press Check. Then write the same time on the other clock.
- Two with no slips moves you up a level. Level 1 has whole and half hours, level 2 any five minutes, and level 3 the tricky ones around midnight and noon.
3. How long does it take?
Key idea
To find how long something takes, count on along a time number line. Jump to the next o’clock,
then jump whole hours, then jump the minutes left. Add up the jumps.
Example 1: a coach leaves at 09:50 and arrives at 11:25. How long is the journey?
- Jump to the next o’clock:09:50 to 10:00 = 10 minutes
- Jump whole hours:10:00 to 11:00 = 1 hour
- Jump the minutes left:11:00 to 11:25 = 25 minutes
- Add the jumps:10 + 25 = 35 minutes, and 1 hour
Answer1 hour 35 minutes
Example 2: a film starts at 18:40 and lasts 1 hour 55 minutes. When does it end?
- 1 hour 55 minutes is 5 minutes less than 2 hours. Add 2 hours:18:40 + 2 hours = 20:40
- Then take the 5 minutes back off:20:40 − 5 minutes = 20:35
AnswerThe film ends at 20:35.
Watch out
Never take away times like ordinary numbers. 1125 − 950 = 175, but the journey is not “1 hour 75
minutes”. An hour has only 60 minutes, so count on instead.
Time jumps
How it works
- Type the size of each jump. The number line draws it for you. Then add the jumps up.
- Two with no slips moves you up a level. Level 1 stays inside one hour, level 2 crosses an o’clock, level 3 takes hours, level 4 uses afternoon times on the 24-hour clock, and level 5 goes past midnight.
4. Bus and train timetables
Key idea
In a timetable, each column is one bus or train. Read down a column to follow it from stop to
stop. Each row is one stop: read across to see every bus that stops there. A dash (–)
means that bus does not stop there.
| Stop | Bus A | Bus B | Bus C | Bus D |
|---|---|---|---|---|
| Bus Station | 07:50 | 08:20 | 08:45 | 09:15 |
| Park Road | 08:02 | 08:32 | – | 09:27 |
| Market Square | 08:15 | 08:45 | 09:05 | 09:40 |
| Hill School | 08:28 | 08:58 | 09:17 | 09:53 |
Example 1: Ali gets to Park Road at 08:10. When is the next bus, and how long does he wait?
- Read across the Park Road row. The first time after 08:10 is Bus B:08:32
- Count on from 08:10:08:10 to 08:32 = 22 minutes
AnswerThe 08:32 bus. Ali waits 22 minutes.
Example 2: how long does Bus C take from the Bus Station to Hill School?
- Read down the Bus C column:it leaves at 08:45 and arrives at 09:17
- Count on:15 minutes to 09:00, then 17 more: 15 + 17 = 32
Answer32 minutes
Example 3: Mia must be at Hill School by 09:00. Which is the latest bus she can catch from the Bus Station?
- Read across the Hill School row for the last time before 09:00:08:58 (Bus B)
- Read up the Bus B column to the Bus Station:08:20
AnswerThe 08:20 bus. The next one, Bus C, arrives at 09:17: too late.
Watch out
Stay in one column when you follow a journey: do not jump to a different bus halfway down. And a bus
with a dash at your stop is no use to you, however good its other times look.
Catch the bus
How to play
- Tap the times in the timetable that the question asks for. When you get there, the bus (or train) sets off along its route.
- Two with no slips moves you up a level. Level 1 is finding times, level 2 is how long a journey takes, and level 3 is planning: which one to catch, and how long you wait.
5. Time zones
Key idea
The Earth spins, so morning comes to different places at different times. Countries set their clocks to suit
their own day, so clocks around the world show different times: these are time zones. Places to the
east of the UK are ahead (their clocks are later): add the difference. Places to the
west are behind: take away the difference.
When it is 12 noon in London in January
← west: behindeast: ahead →
New York5 hours behind07:00Monday
LondonLondon12:00Monday
Paris1 hour ahead13:00Monday
Dubai4 hours ahead16:00Monday
Tokyo9 hours ahead21:00Monday
These are the differences in January. In summer, some of them change by an hour, because some countries put their clocks forward for the summer and some do not. A question will always tell you the difference to use.
Example 1: it is 10:00 in London. Tokyo is 9 hours ahead. What time is it in Tokyo?
- Ahead, so add:10 + 9 = 19
Answer19:00, or 7 pm
Example 2: it is 20:00 on Monday in London. What time is it in Tokyo?
- Add 9 hours:20 + 9 = 29
- That is past midnight, so take away 24, and it is the next day:29 − 24 = 5
Answer05:00 on Tuesday
Example 3: a plane leaves London at 09:00 London time. The flight takes 7 hours. Dubai is 4 hours ahead of London. What time is it in Dubai when it lands?
- Add the flight time, in London time:09:00 + 7 hours = 16:00
- Dubai is 4 hours ahead, so add 4:16:00 + 4 hours = 20:00
Answer20:00 in Dubai
Watch out
Ahead means add, behind means take away. If the time goes past midnight, the day changes
too.
World clocks
Drag the red marker to change the time in London. Watch every clock change with it.
How to play
- Play with the marker first. Then answer the question underneath: the clock you need hides its time until you have answered.
- Two with no slips moves you up a level. Level 1 is places ahead of London, level 2 adds places behind and going past midnight, and level 3 is flights.
6. Calendars and leap years
Key idea
A year has 12 months and 365 days. Most months have 30 or 31 days. February has
28, or 29 in a leap year, which makes that year 366 days long. Every 7 days
it is the same day of the week again.
The knuckle trick
Make a fist. Every month on a knuckle has 31 days. Every month in a dip has 30, except February. Or learn the old rhyme: “Thirty days has September, April, June and November”.
Example 1: 3 March 2027 is a Wednesday. What day of the week is 24 March 2027?
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 22 | 23 | 24 | 25 | 26 | 27 | 28 |
| 29 | 30 | 31 |
- How many days later?24 − 3 = 21
- 21 days is exactly 3 weeks, and every 7 days it is the same day again:21 = 3 × 7
AnswerWednesday
Example 2: how many days is it from 25 March to 4 April?
- March has 31 days. From 25 March to the end of March:31 − 25 = 6
- Then 4 more days into April:6 + 4 = 10
Answer10 days
Example 3: is 2036 a leap year?
- Does it divide exactly by 4?2036 ÷ 4 = 509
AnswerYes. 2036 is a leap year.
Leap years
A year is a leap year if it divides exactly by 4: 2024, 2028, 2032. A quick check: if the
last two digits make a number in the 4 times table, it is a leap year (2036: 36 is in the 4 times
table). There is one extra rule for years ending in 00: they are only leap years if they divide exactly
by 400. So 2000 was a leap year, but 1900 was not.
Watch out
“From 25 March to 4 April” is 10 days: do not count both the first day and the last. If a
question says including both days, add 1.
Calendar detective
How to play
- Some dates are missing. Tap the square where the date belongs: count on in 7s down a column.
- Two with no slips moves you up a level. Level 1 stays in one month, level 2 goes into the next month, and level 3 counts the days between two dates.
Leap year or not?
How to play
- Is the year a leap year? Check the last two digits, and remember the rule for years ending in 00.
- Two in a row with no slips moves you up a level. Level 1 has years near today, level 2 any year, and level 3 adds years ending in 00.
7. Problems with time
Key idea
Put everything into the same unit before you add, take away or compare. Use the 24-hour clock in
your working, so am and pm cannot get mixed up. Then count on, as in section 3.
Example 1: school starts at 08:50 and ends at 15:20. Lunch and breaks take 1 hour 10 minutes. How long are the lessons?
- Count on from 08:50 to 15:20:10 minutes + 6 hours + 20 minutes = 6 hours 30 minutes
- Take away the breaks:6 hours 30 minutes − 1 hour 10 minutes = 5 hours 20 minutes
Answer5 hours 20 minutes
Example 2: how many seconds are there in a quarter of an hour?
- A quarter of an hour in minutes:60 ÷ 4 = 15
- Each minute is 60 seconds:15 × 60 = 900
Answer900 seconds
Watch out
Read the question for its unit. If it asks for the answer in minutes, 1 hour 35 minutes must become
95 minutes.
Time workshop
How it works
- Follow the steps and type each answer. For a time, use the : key, like 20:35.
- Two with no slips moves you up a level. Level 1 is hours, minutes, days and weeks, level 2 adds seconds and parts of an hour, level 3 is start and end times, level 4 is journeys and time zones, and level 5 has two-step problems.
8. Practice: pick your level
Start with Foundation if you are in Year 4 or just starting. Move up when you are getting most of them right.
The mistakes that cost marks
- Treating time like decimals. Saying 1.5 hours is 1 hour 50 minutes. an hour has 60 minutes, so half an hour is 30: 1.5 hours is 1 hour 30 minutes.
- Taking away times like ordinary numbers. 11:25 − 09:50 is not 1 hour 75 minutes. count on: 10 minutes, then 1 hour, then 25 minutes: 1 hour 35 minutes.
- Reading the short hand too early. Calling a clock with the short hand nearly on the 4 “4:45”. the hour only changes when the long hand reaches the 12. It is 3:45.
- Adding 12 to the wrong times. Writing 12:30 pm as 24:30, or 12:30 am as 12:30. 12:30 pm is 12:30, and 12:30 am is 00:30. Only add 12 from 1 pm onwards.
- Leaving out a digit. Writing 9:05 am as 9:05 on the 24-hour clock. the 24-hour clock always has four digits: 09:05.
- Jumping between columns in a timetable. follow one bus or train straight down its own column.
- Mixing up ahead and behind. ahead means add the difference; behind means take it away. Past midnight, change the day.
- Forgetting the 00 rule. Saying 1900 was a leap year because it divides by 4. a year ending in 00 must divide by 400. 2000 was a leap year; 1900 was not.
- Counting both ends. Saying 25 March to 4 April is 11 days. it is 10 days. Only add 1 if the question says “including” both days.
Quick checklist
Tick each one when you can do it without help.
All ticked. Brilliant work! You have finished Lesson 6.5.
Download
Print these and work through them away from the screen.
All of this is free
Every 11+ maths resource on this site is free, with no account needed. Taught sessions are currently GCSE maths only — if you would like a group opened for this subject, join the waiting list and it helps me decide what to run next.
Join the waiting list →