Understand the idea.
Bridge through a convenient time
Elapsed time is a duration between two clock readings. It needs units such as minutes or hours. Since an hour contains minutes, the digits after a clock’s colon do not behave like decimal hundredths.
Count forward in manageable jumps: reach the next full hour, add any whole hours, then count to the arrival minute. Add the durations of the jumps. This keeps the change of hour visible rather than hiding it in subtraction.
Keep track of the day
Check the day as well as the time. After comes on the next day. For a journey crossing midnight, find the minutes remaining in the first day, then add the minutes into the next.
Test a duration by adding it back to the departure. For example, a journey lasting minutes can be added as one hour and minutes. The result must land on the stated arrival time and day.
See the method in action.
Cross an hour
A train departs at 08:47 and arrives at 10:12 on the same day. How long is the trip?
Worked solution
- 1
Count to the next full hour.
The first jump uses the minutes remaining in the eight o’clock hour.
- 2
Count the full hour and final minutes.
One complete hour ends at 10:00, followed by twelve minutes.
- 3
Combine the durations.
The consecutive jumps cover the entire trip without gaps.
- 4
Express the duration in hours and minutes.
Sixty of the eighty-five minutes make one hour, leaving twenty-five minutes.
85 minutes, or 1 hour 25 minutes.
Cross midnight
A bus leaves at 23:35 and arrives at 00:20 the next day. Find the journey time.
Worked solution
- 1
Count from departure to midnight.
Midnight is the start of the next day, reached after the remaining twenty-five minutes of this hour.
- 2
Count from midnight to arrival.
The arrival is twenty minutes into the new day.
- 3
Add the two parts.
The journey continues across midnight, so both parts belong to its duration.
45 minutes.
Try it yourself.
Check your understanding
How long is 14:50 to 15:15?
Show answer & reasoning
25 minutes
From to is minutes; from there to is minutes. Their sum is minutes.
Keep practising
6 worksheet questions · 13 marks
Read the questions online
- Find the elapsed time from 09:25 to 10:05.2 marks
- Find the elapsed time from 13:48 to 15:06.2 marks
- A journey starts at 11:40 and lasts 55 minutes. When does it finish?2 marks
- You must arrive at 16:05 after a trip of 1 hour 25 minutes. What is the latest departure time?2 marks
- A coach leaves at 22:50 and arrives at 01:15 the next day. Find its journey time.2 marks
- An outing starts at 08:40. It has 30 minutes of travel, a 15-minute wait, a 45-minute activity and 20 minutes of travel home. When does it finish?3 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Find the elapsed time from 09:25 to 10:05.2 marks
09:25 to 10:00 is 35 minutes.
Add 5 minutes: 40 minutes.
40 minutes - Find the elapsed time from 13:48 to 15:06.2 marks
12 minutes to 14:00, then 60 minutes to 15:00, then 6 minutes.
.
78 minutes, or 1 hour 18 minutes - A journey starts at 11:40 and lasts 55 minutes. When does it finish?2 marks
20 minutes reach 12:00.
There are 35 minutes left, so the finish is 12:35.
12:35 - You must arrive at 16:05 after a trip of 1 hour 25 minutes. What is the latest departure time?2 marks
Subtract 1 hour to 15:05.
Subtract 25 minutes to 14:40.
14:40 - A coach leaves at 22:50 and arrives at 01:15 the next day. Find its journey time.2 marks
70 minutes reach midnight.
75 more minutes reach 01:15.
minutes.
2 hours 25 minutes, or 145 minutes - An outing starts at 08:40. It has 30 minutes of travel, a 15-minute wait, a 45-minute activity and 20 minutes of travel home. When does it finish?3 marks
minutes.
.
10:30
Curriculum reference & lesson scope
Australian Curriculum v9 / SA Curriculum Mathematics
Year 6: itineraries, elapsed time and feasible journey planning, including connections and 24-hour time.
Official curriculum source ↗