Start time and end time
A club starts at 2:15 and ends at 2:45. Count on from 2:15 to 2:45.
15 + 15 = 30, so the club lasts 30 minutes.
Year 3
Compare durations of events
Find how long an event lasts and when it ends by counting on, then compare durations.
Lesson overview
Time
A duration is how long something lasts. To find a duration, count on from the start time to the end time. To find an end time, count on the duration from the start time. Use the next hour as a stepping stone when you need to. Then you can compare durations to decide which event is shorter, longer or lasts the same amount of time.
Start time and duration
A show starts at 3:20 and lasts 25 minutes. Count on 25 minutes from 3:20.
Split 25 minutes into 20 + 5. The show ends at 3:45.
Count on to the next hour
A lesson starts at 10:50 and ends at 11:20. Count on to 11:00 first, then count on to 11:20.
10 + 20 = 30, so the lesson lasts 30 minutes.
Worked example
A club runs from 1:45 to 2:20. A film lasts 1 hour. Which lasts longer?
- Count on from 1:45 to the next hour: 1:45 to 2:00 is 15 minutes.
- Count on from 2:00 to 2:20, which is 20 minutes. 15 + 20 = 35, so the club lasts 35 minutes.
- Remember that 1 hour is 60 minutes, so compare 35 minutes with 60 minutes.
- 60 is greater than 35, so the film lasts longer.
Try it
Count on from the start time in jumps, using the next hour if you need it. Compare durations in the same unit.
Question 1
Which lasts longer?
Question 2
Which order is shortest to longest?
Question 3
A bus journey starts at 5:40 and ends at 6:05. How many minutes does it last?
Question 4
A game starts at 6:20 and lasts 25 minutes. What time does it end?
Question 5
Which statement is correct?
Common mistakes
Watch for these when working through the lesson.
- Comparing only the numbers without the units.
- Thinking 1 hour is less because the number 1 is small.
- Mixing up shortest to longest and longest to shortest.
- Forgetting to stop at the next hour, such as counting 10:50 to 11:20 as 20 minutes instead of 10 + 20 = 30 minutes.
- Counting on the wrong number of minutes when adding a duration to a start time.
Related topics
These ideas fit closely with this lesson.
- Record and compare time in terms of seconds, minutes and hours.
- Know the number of seconds in a minute and the number of days in each month, year and leap year.