Choose the right unit
A sprint might take seconds. A lesson might last an hour.
The best unit depends on how long the event lasts.
Year 3
Record and compare time in terms of seconds, minutes and hours
Use seconds, minutes and hours to record and compare durations.
Lesson overview
Time
Short events can be measured in seconds, medium events in minutes and longer events in hours. Comparing time means deciding which interval is longer, shorter or equal.
Compare intervals
45 minutes is shorter than 1 hour.
1 hour is 60 minutes, so 45 minutes is less.
Record times clearly
A film might last 1 hour 30 minutes.
| Event | Time |
|---|---|
| Sprint | 12 seconds |
| Reading | 20 minutes |
| Film | 1 hour 30 minutes |
The written record should match the size of the interval.
Worked example
Which is longer: 90 seconds or 2 minutes?
- Convert 2 minutes into seconds if it helps.
- 2 minutes is 120 seconds.
- 120 seconds is greater than 90 seconds.
- So 2 minutes is longer.
Try it
Choose the best unit first, then compare the size of the time intervals carefully.
Question 1
Which unit is best for a race that lasts 12?
very short
short
longer
Question 2
Which is longer?
Question 3
How many seconds are in 2 minutes?
Question 4
Which event is most likely to last hours?
Question 5
Which statement is true?
Common mistakes
Watch for these when working through the lesson.
- Comparing the numbers without noticing the units.
- Using hours for very short events.
- Forgetting that 1 minute is 60 seconds.
Related topics
These ideas fit closely with this lesson.
- Know the number of seconds in a minute and the number of days in each month, year and leap year.
- Compare durations of events.