Understand the idea.
Use useful jumps
Duration is how long an event lasts between its start and finish. Count forward from the start time to the finish time. If both times are in the same hour, compare just their minute parts.
When you cross an hour, jump to the next whole hour first. From to takes minutes. Then count the minutes from that whole hour to the finish.
Keep track of each part
Keep a record of each jump so no time is missed or counted twice. From to , the jumps are minutes and minutes, making minutes altogether.
To find a finish time, use up the stated duration in the same way. After minutes, the next minute begins a new hour. The minute part never becomes , or .
See the method in action.
Reading time
A class reads from 11:10 to 11:35. How long is that?
Worked solution
- 1
Check whether the hour changes.
Both 11:10 and 11:35 are within the eleven o’clock hour.
- 2
Find the difference in minutes.
There are 25 minute steps from 10 minutes past to 35 minutes past.
- 3
Check by counting forward.
Adding the duration to the start minutes reaches the finish minutes without crossing an hour.
25 minutes.
A game crosses the hour
A game starts at 2:50 and lasts 25 minutes. When does it finish?
Worked solution
- 1
Jump from the start to the next hour.
Ten of the 25 minutes take the clock from 2:50 to 3:00.
- 2
Find the duration still to use.
The first jump has used ten minutes of the game.
- 3
Count on the remaining minutes.
Fifteen minutes after three o’clock gives the finish time 3:15.
3:15.
Try it yourself.
Check your understanding
How long is it from 9:55 to 10:05?
Show answer & reasoning
10 minutes
Count minutes from to , then more to . The duration is minutes.
Keep practising
6 worksheet questions
Read the questions online
- A lesson starts at 9:15 and ends at 9:40. Find its duration.
- A bus leaves at 1:45 and arrives at 2:10. How long is the trip?
- A game begins at 4:05 and lasts 20 minutes. Find the finish time.
- A cake goes in the oven at 10:40 for 30 minutes. When is it ready?
- Which lasts longer: 8:20 to 8:50, or 1:10 to 1:35?
- A train leaves at 3:30 and arrives at 4:30. A child says it takes 100 minutes. Correct the answer.
Read the worked solutions
- A lesson starts at 9:15 and ends at 9:40. Find its duration.
Count forward from 15 past to 40 past.
25 minutes - A bus leaves at 1:45 and arrives at 2:10. How long is the trip?
15 minutes to 2:00 and 10 more minutes make 25.
25 minutes - A game begins at 4:05 and lasts 20 minutes. Find the finish time.
Add 20 minutes to 4:05.
4:25 - A cake goes in the oven at 10:40 for 30 minutes. When is it ready?
20 minutes to 11:00 and 10 more minutes.
11:10 - Which lasts longer: 8:20 to 8:50, or 1:10 to 1:35?
The durations are 30 minutes and 25 minutes.
8:20 to 8:50, by 5 minutes. - A train leaves at 3:30 and arrives at 4:30. A child says it takes 100 minutes. Correct the answer.
The times are exactly one hour apart.
An hour contains 60 minutes.
60 minutes, or 1 hour.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum
Analogue/digital clocks to the minute; seconds/minutes/hours/days; duration.
Official curriculum source ↗