The idea in brief. Starting time, finishing time and duration determine one another; choose the direction before stepping across hours. Decide whether you are finding a clock time or a duration. Cross midnight in the correct direction. In the lesson. You can read the 24-hour clock. Today we find starting times, finishing times and durations. A puppet show starts at 08 50 and lasts 25 min. At what time does it finish? Use the 24-hour clock. Move forwards for the finish and backwards for the start.
Lesson video, with the working
Starting time, finishing time and duration
6 min 23 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
How do you solve start time, end time and duration questions in P3?
This page teaches finding a finishing time, a starting time or a duration when the other two are given.
What your child learns here
This page teaches finding a finishing time, a starting time or a duration when the other two are given. It follows the P3 outcome on starting time, finishing time and duration, and uses the 24-hour clock and timelines.
Decide which of the three is missing: the starting time, the finishing time or the duration.
Count forwards on a timeline to find a finishing time, jumping to the next hour first.
Count backwards from the finish to find a starting time.
Find a duration by counting from the start to the finish in hours and minutes.
Cross midnight correctly when an event starts on one day and ends on the next.
Does the answer make sense?
A finishing time must come after the start on the same day. The hours part of a duration equals the difference between the two hour numbers, or one less when the finishing minutes are smaller than the starting minutes, so your child can check it before counting the minutes.
How to practise these questions
The Basic questions practise finding a duration, a finishing time or a starting time when the length is under an hour. The Intermediate questions add durations of several hours and times that cross noon, so counting on to the next hour comes first. If a duration question stalls, view the solution film for it and try once more later from Revision.
Questions parents ask
What does duration mean in P3 maths? Duration is how long something lasts, from its starting time to its finishing time. The Primary 3 syllabus asks children to find any one of starting time, finishing time or duration when the other two are given.
Why use a timeline for time questions? A timeline turns clock times into jumps your child can see, usually to the next hour and then the rest. It keeps clock times from being subtracted like ordinary numbers, since an hour has 60 minutes.
Does my child need the 24-hour clock for duration questions? Many questions on this page give times on the 24-hour clock, so it helps to be comfortable reading it first. The 24-hour clock lesson comes just before this one in the chapter.
