12- and 24-Hour Time: a week of ready-to-teach maths
Five days of lessons for Year 5 Measurement. Print this pack and the week is prepared: each day has a one-page plan and a student worksheet, plus twenty-four time-pair cards, a day line to cut out, a mini-check and every answer.
Start here: five minutes to Monday
- Skim the week at a glance on the next page.
- Print the five days. Each day is two A4 sheets: a plan and a worksheet.
- Cut out the time-pair cards once (keep each set in an envelope), and a day line for each child.
- Open the free interactive unit on your board. Every plan tells you which picture to show and which buttons to press.
- Teach straight from the plan. Timings, talk prompts, misconceptions and answers are all on the one page.
No maths background needed
This pack is written for the busy generalist teacher. Each plan explains the idea in plain words, lists the misconceptions children bring, and gives the answers. The big idea of the week: the 12-hour clock counts 1 to 12 twice a day with am and pm, and the 24-hour clock counts the hours straight through from 00 to 23. Morning hours look the same in both; afternoon hours add twelve, so 3:30 pm is 15:30. The two traps are the twelves: 12:15 am is 00:15, and 12:15 pm stays 12:15.
One day, one lesson
The five lessons fill a week of maths, one lesson of about 50 minutes a day. Run them in order: each day stands on the one before. Every plan marks a split point if your timetable runs two shorter sessions.
The week at a glance
One lesson a day for a week. Each day stands on the day before, so run them in order.
| Day | Lesson | Children learn and do | On screen |
|---|---|---|---|
| 1 | Two ways to tell the time | Match the same moment in both systems, place a day on a day line, and compare the two systems | Two ways to tell the time |
| 2 | From 12-hour to 24-hour | Keep am hours, add twelve to pm hours, and take care with 12 am and 12 pm | From 12-hour to 24-hour time |
| 3 | From 24-hour to 12-hour | Read hours below 12 as am and take twelve from 13 to 23 for pm, from lists and digital clocks | From 24-hour to 12-hour time |
| 4 | Noon, midnight and how long | Write moments near noon and midnight both ways, and find how long between two times | Noon, midnight, am and pm |
| 5 | Timetables | Read a bus timetable in 24-hour time: departures, trip times and waits; play the unit quiz | Solving problems with time |
How the week builds
Day 1 compares the two systems; Days 2 and 3 convert each way; Day 4 handles noon, midnight and durations; and Day 5 uses it all on a real timetable. It builds on Year 4’s durations with am and pm and conversions between units of time (AC9M4M03), and it leads to Year 6, where children interpret timetables and itineraries to plan journeys (AC9M6M03).
Materials for the week (one trip)
- From the classroom: an analogue clock, any digital clock set to 24-hour time, scissors, sticky tape, envelopes, this pack printed.
- Cut out once: the twenty-four time-pair cards (Day 1) and a day line per child (Days 2 to 4). A real bus or train timetable is a bonus for Day 5.
Words for the word wall
am, pm, noon, midnight, 12-hour time, 24-hour time, timetable, depart, arrive, duration
Dear families
This week in maths, Year 5 compares 12-hour time (with am and pm) and 24-hour time (00 to 23). Morning times look the same in both; afternoon times add twelve, so 3:30 pm is 15:30. Watch the twelves: 12:15 am is 00:15, and 12:15 pm is 12:15.
Try this at home
- Find a 24-hour clock at home (an oven, a microwave, a phone setting). Read it both ways.
- Say a time such as 7:40 pm; your child says it in 24-hour time. Then swap.
- Look at a bus, train or cinema timetable together. When does the next one leave, in am or pm?
- Ask: how long from 4:45 pm to 6:10 pm? How did you count on?
Times I spotted this week
Fill one row a day. Write a time you saw, then write it the other way.
| Day | Where | 12-hour | 24-hour |
|---|---|---|---|
| Monday | |||
| Tuesday | |||
| Wednesday | |||
| Thursday | |||
| Friday |
Printed from the free seegongsik 12- and 24-Hour Time teaching pack · seegongsik.com/au/y5/measurement/AC9M5M03/pack
Two ways to tell the time
Children compare the two systems. The 12-hour clock counts 1 to 12 twice a day and needs am or pm; the 24-hour clock counts the hours since midnight, 00 to 23, and needs neither. On a day line, 7:15 pm sits 19 hours and 15 minutes after midnight, so it is 19:15.
We are learning to
- match the same moment in 12-hour and 24-hour time,
- see how each system counts the hours of a day,
- compare what each system does well.
Success criteria
- I can match a 12-hour time with its 24-hour time.
- I can say one thing each system does well.
You need
The time-pair cards (cut-out sheet 1), one set per group. An analogue clock, and a digital clock set to 24-hour time if you have one. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Same moment Show the board (see the box). Children say the 24-hour time before each new time appears. Ask: “9:00 am and 09:00 look almost the same. Why do 3:30 pm and 15:30 look so different?” |
| 30 min | Pairs and the day line Model 7:15 pm on the day line (above). Groups play time pairs for ten minutes, then children do Parts A and B. Ask: “Count the hours from midnight. What is the 24-hour clock counting?” |
| 10 min | Which is better? Children do Part C. Ask: “Why might a train timetable choose 24-hour time?” |
Two half-sessions instead? Split after the pairs game; start Session B with Part A.
Watch for these ideas
- Thinking the 24-hour clock runs from 1 to 24. It starts at 00, and its last hour is 23.
- Matching by the minutes alone: 9:05 pm with 09:05. Check am or pm first.
- Reading 12:30 am as half past noon. 12 am is the hour after midnight.
Answers
- Part A: wake up 06:45, recess 10:50, lunch 12:30, home time 15:10, dinner 18:15, bed 20:30.
- Part B: not the same, same, same, not the same, not the same, same. Part C: answers vary; for example, 24-hour time needs no am or pm and sorts in order, but it has to be changed back to say it the everyday way.
Two ways to tell the time
A. Mark each event on the day line, then write its 24-hour time
| Event | 12-hour time | 24-hour time |
|---|---|---|
| Wake up | 6:45 am | |
| Recess | 10:50 am | |
| Lunch | 12:30 pm | |
| Home time | 3:10 pm | |
| Dinner | 6:15 pm | |
| Bed | 8:30 pm |
B. Same moment or not? Write same or not the same.
C. Which is better?
Write one way 24-hour time is easier than 12-hour time, and one way it is harder.
From 12-hour to 24-hour
The rule has two parts and two exceptions. An am time keeps its hour; a pm time adds twelve to the hour, so 4:20 pm is 16:20. The exceptions are the twelves: 12 am is the hour after midnight, so 12:05 am is 00:05, and 12 pm is the hour after noon, so it stays 12. The minutes never change.
We are learning to
- change an am time to 24-hour time,
- change a pm time to 24-hour time by adding twelve to the hour,
- handle 12 am and 12 pm.
Success criteria
- I can write any 12-hour time in 24-hour time.
- I can explain why 12:15 pm and 12:15 am are written differently.
You need
A day line for each child (cut-out sheet 2). Mini whiteboards. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Add twelve? Show the board (see the box). Children write their answer on whiteboards before anyone presses. Ask: “Why does 7:00 am not change, when 3:30 pm does?” |
| 30 min | Am, pm and the twelves Model 4:20 pm → 16:20 and 12:05 am → 00:05 on the day line. Children do Parts A and B. Ask: “Find 12 noon on your day line. What happens to the hours after it?” |
| 10 min | Which is later? Children do Part C. Ask: “Could you compare the two times without changing one of them?” |
Two half-sessions instead? Split after Part A; start Session B with the two model times again.
Watch for these ideas
- Adding twelve to an am time, as in 7:00 am written as 19:00.
- Adding twelve to 12 pm: 12:10 pm written as 24:10. Noon stays 12.
- Leaving 12 am as 12: 12:40 am written as 12:40. The hour after midnight is 00.
Answers
- Part A: 6:15 am = 06:15; 1:40 pm = 13:40; 11:05 pm = 23:05; 12:25 pm = 12:25; 12:50 am = 00:50; 9:30 pm = 21:30; 10:10 am = 10:10; 7:55 pm = 19:55.
- Part B: 08:50, 16:15, 21:00, 07:30. Part C: 7:45 pm is 19:45, so it is later than 19:30.
From 12-hour to 24-hour
A. Write each time in 24-hour time
| 12-hour | 24-hour | 12-hour | 24-hour |
|---|---|---|---|
| 6:15 am | 12:50 am | ||
| 1:40 pm | 9:30 pm | ||
| 11:05 pm | 10:10 am | ||
| 12:25 pm | 7:55 pm |
B. Everyday times
| Event | 12-hour | 24-hour |
|---|---|---|
| School starts | 8:50 am | |
| Swimming lessons begin | 4:15 pm | |
| The fireworks start | 9:00 pm | |
| The shop opens | 7:30 am |
C. Which is later?
Which is later: 7:45 pm or 19:30? Write both in 24-hour time to decide.
From 24-hour to 12-hour
The rule runs backwards. Hours 00 to 11 are am; hours 12 to 23 are pm, and from 13 to 23 twelve is taken from the hour, so 18:40 is 6:40 pm. The twelves again need care: 12 stays 12 (pm), and 00 is 12 am, so 00:20 is 12:20 am. Say am or pm every time.
We are learning to
- decide from the hour whether a 24-hour time is am or pm,
- take twelve from the hours 13 to 23,
- read 00 as 12 am and 12 as 12 pm.
Success criteria
- I can write any 24-hour time in 12-hour time, with am or pm.
- I can read a digital clock set to 24-hour time.
You need
The day lines from Day 2. A digital clock set to 24-hour time, if you have one. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Take twelve? Show the board (see the box). Children write their answer on whiteboards before anyone presses. Ask: “06:40 is below 12. What does that tell you before you do anything else?” |
| 30 min | Below 12, 12 and above Model 18:40 → 6:40 pm and 00:20 → 12:20 am on the day line. Children do Parts A and B. Ask: “Which hours do not need twelve taken away? Why?” |
| 10 min | Fix the mistake Children do Part C. Ask: “How could Sam check his answer on the day line?” |
Two half-sessions instead? Split after Part A; start Session B with the digital clocks.
Watch for these ideas
- Taking away ten instead of twelve, as in 17:00 read as 7 pm.
- Taking twelve from the 12 hour: 12:20 written as 0:20 pm. The 12 hour stays 12, and it is pm.
- Dropping am or pm: 21:00 written as 9:00. Without am or pm the time could be either.
Answers
- Part A: 07:25 = 7:25 am; 14:10 = 2:10 pm; 22:35 = 10:35 pm; 12:05 = 12:05 pm; 00:40 = 12:40 am; 19:00 = 7:00 pm; 11:55 = 11:55 am; 16:45 = 4:45 pm.
- Part B: 5:50 am, 1:15 pm, 8:30 pm, 12:05 am. Part C: Sam took ten from the hour; 15:00 is 3:00 pm, because 15 − 12 = 3.
From 24-hour to 12-hour
A. Write each time in 12-hour time, with am or pm
| 24-hour | 12-hour | 24-hour | 12-hour |
|---|---|---|---|
| 07:25 | 00:40 | ||
| 14:10 | 19:00 | ||
| 22:35 | 11:55 | ||
| 12:05 | 16:45 |
B. Read each digital clock in 12-hour time
C. Fix the mistake
Sam says 15:00 is 5 pm. Explain his mistake and write the right time.
Noon, midnight and how long
Noon and midnight are where the two systems differ most: 12 noon is 12:00, and 12 midnight is 00:00, the start of a new day. Durations are counted on in jumps along the day line: from 10:40 to 13:15 is 20 min to the next hour, 2 h, then 15 min, so 2 h 35 min. Jumping past noon or midnight needs no new rule.
We are learning to
- write moments near noon and midnight in both systems,
- find how long it is from one time to another by counting on,
- count on past noon and past midnight.
Success criteria
- I can write 10 minutes after midnight in both systems.
- I can find how long between two times, even across midnight.
You need
The day lines from Day 2. Mini whiteboards. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Which half of the day? Show the board (see the box). Children vote with fingers before anyone presses. Ask: “Why is noon not 00:00? What happens at 00:00?” |
| 30 min | Count on in jumps Model 10:40 to 13:15 on the day line in three jumps (above). Children do Parts A and B. Ask: “Where is your first jump to? Why is an o’clock a good place to land?” |
| 10 min | Overnight Children do Part C. Ask: “The train leaves one day and arrives the next. Where does midnight come into your jumps?” |
Two half-sessions instead? Split after Part A; start Session B with the model jumps again.
Watch for these ideas
- Calling noon 12 am. Noon starts the pm half of the day.
- Taking one time from the other as if an hour had 100 minutes: 10:40 to 13:15 worked out as 1315 − 1040 = 275.
- Getting stuck at midnight: 22:10 to 01:00 has no answer by taking away. Count on through 00:00.
Answers
- Part A: 12:20 am = 00:20; 11:55 am = 11:55; 12:30 pm = 12:30; 11:50 pm = 23:50.
- Part B: 2 h 25 min; 3 h 40 min; 2 h 30 min; 3 h 15 min. Part C: 9:40 pm to 7:05 am, 9 h 25 min.
Noon, midnight and how long
A. Write each moment in both systems
| Moment | 12-hour | 24-hour |
|---|---|---|
| 20 minutes after midnight | ||
| 5 minutes before noon | ||
| half an hour after noon | ||
| 10 minutes before midnight |
B. How long from the first time to the second?
| From | To | My jumps | How long |
|---|---|---|---|
| 09:15 | 11:40 | ||
| 10:25 | 14:05 | ||
| 15:50 | 18:20 | ||
| 21:35 | 00:50 |
C. Overnight
An overnight train leaves at 21:40 and arrives at 07:05 the next morning. Write both times in 12-hour time. How long is the trip?
Timetables
Timetables use 24-hour time because a list sorts itself in order with no am or pm. Children read a bus timetable down a column for one trip and across a row for one stop, change times to 12-hour time to say them, and count on to find trip times and waits.
We are learning to
- read a 24-hour timetable down a column and across a row,
- say timetable times in 12-hour time,
- find trip times and waits, and choose the right bus.
Success criteria
- I can find when a bus reaches a stop, and say it in 12-hour time.
- I can choose a bus that gets me somewhere on time.
You need
A real local bus or train timetable, if you can print one. The worksheet, one per child.
Lesson flow (about 50 minutes)
| 10 min | Convert in context Show the board (see the box). Children say the answer in words before anyone presses. Ask: “The ticket says 19:30. What would you tell a friend who asks when the show starts?” |
| 30 min | Read the timetable Model one column and one row: Trip 1 reaches the Market at 07:10, which is 7:10 am; the Library row lists 06:58, 08:28, 12:43, 18:03. Children do Parts A and B. Ask: “To be somewhere by a time, why look for the bus that arrives just before it?” |
| 10 min | Quiz game Run the unit’s self-check quiz as a class game: pairs agree on an answer before it is pressed. Early finishers do Part C. |
Two half-sessions instead? Split after Part A; start Session B with Part B.
Watch for these ideas
- Reading the wrong column or row. Keep a finger on the trip and a ruler under the stop.
- Choosing a bus that arrives after the time needed. It must arrive at or before it.
- Changing only the hour, as in 17:50 read as 5:50. Say am or pm.
Answers
- Part A: 1. 12:30 pm. 2. 39 min. 3. Trip 2, which reaches the Market at 08:40. 4. 6:29 pm. 5. 8 min, for Trip 3 at 12:43.
- Part B: 5:50 pm, 6:03 pm, 6:15 pm, 6:29 pm. Part C: questions vary; check the partner’s answer on the table.
Timetables
Route 7 bus timetable
| Stop | Trip 1 | Trip 2 | Trip 3 | Trip 4 |
|---|---|---|---|---|
| Beach Road | 06:45 | 08:15 | 12:30 | 17:50 |
| Library | 06:58 | 08:28 | 12:43 | 18:03 |
| Market | 07:10 | 08:40 | 12:55 | 18:15 |
| Station | 07:24 | 08:54 | 13:09 | 18:29 |
A. Use the timetable
2. How long does a bus take from Beach Road to the Station? ______________
3. Mia must be at the Market by 9:00 am. Which trip should she catch? ______________
4. In 12-hour time, when does the last bus reach the Station? ______________
5. Ben reaches the Library stop at 12:35 pm. How long does he wait for a bus? ______________
B. Write the times for Trip 4 in 12-hour time
C. Your turn
Write a question about the timetable for a partner, and its answer.
Time pairs
Cut out the twenty-four cards (Day 1), one set per group of three or four. Shuffle them face down. Take turns to turn over two cards; keep them if they show the same moment.
Teacher note: twelve pairs, with near misses to catch: 9:05 am and 9:05 pm, 8:00 am and 8:00 pm, 11:20 am and 11:20 pm.
Day line
Cut out the two strips (Days 2 to 4), one per child, and tape the noon ends together to make a whole day. Read 12-hour time above the line and 24-hour time below it. Each small mark is 15 minutes.
Teacher note: midnight sits at both ends of the day: 12 midnight is 00:00, the start of a new day.
What we know: 12- and 24-Hour Time
Work on your own. Show your thinking if you can.
- Write 9:45 pm in 24-hour time. __________
- Write 07:05 in 12-hour time. __________
- Write 12:20 am in 24-hour time. __________
- Write 16:30 in 12-hour time. __________
- Which is later: 8:15 pm or 20:05? __________
- How long is it from 09:40 to 12:05? __________
- What time does this digital clock show, in 12-hour time? __________
- A ferry leaves at 15:40 and the trip takes 55 minutes. When does it arrive, in 12-hour time?
How did this week feel? Circle one: I can teach it · I am getting there · I need more help
Answers and marking guide
Answers
- 21:45
- 7:05 am
- 00:20
- 4:30 pm
- 8:15 pm (8:15 pm is 20:15)
- 2 h 25 min
- 12:00 midnight, also written 12 am
- 16:35, which is 4:35 pm
A quick three-level guide
| Idea | Working towards | At standard | Beyond |
|---|---|---|---|
| 12-hour to 24-hour (Q1, Q3) | adds twelve to every time | keeps am hours and adds twelve to pm hours | explains 12 am and 12 pm |
| 24-hour to 12-hour (Q2, Q4) | drops am or pm, or takes away ten | takes twelve from 13 to 23 and says am or pm | reads a digital clock at a glance |
| Comparing the systems (Q5, Q7) | compares the numbers without converting | converts to one system before comparing | explains why timetables use 24-hour time |
| Practical problems (Q6, Q8) | subtracts times as whole numbers | counts on in jumps to find a duration | counts on past noon or midnight |
Eight questions, four ideas. A child at standard answers most questions and can say why, by deciding am or pm first and then adding or taking away twelve.
Weekly class record
Jot a tick as you move around the room; the mini-check fills any gaps. A tick a day is plenty.
| Name | Matches both forms | To 24-hour | To 12-hour | Noon and how long | Reads a timetable |
|---|---|---|---|---|---|
The five columns are the five days: matching both forms, converting to 24-hour time, converting to 12-hour time, noon, midnight and how long, and reading a timetable.