Time: how long does it take?
The 24-hour clock, the time line trick for time intervals, converting hours and minutes, and bus timetables. Read one step, play with it, then tap “I understand this”.
The 24-hour clock
A day has 24 hours. 24-hour time counts right through from 00:00 (midnight) to 23:59, so you don’t need a.m. or p.m. Buses, planes and TV guides use it.
The day ribbon
Change the hour and the minutes.
How long does it take? Use a time line
Don’t subtract the times like ordinary numbers. Rather jump on a time line: first to the next whole hour, then whole hours, then the minutes that are left.
The time line
Set the start and end time, or tap “New times”.
It works the other way too: a movie starts at 18:45 and lasts 1 h 50 min. Jump 1 h to 19:45, then 15 min to 20:00, then 35 min more: 20:35.
13:20 − 9:45 as ordinary numbers gives 1 320 − 945 = 375. That is nonsense, because an hour has only 60 minutes. The time line jumps over the whole hour, where the minutes start at 0 again.
Hours and minutes
An hour has 60 minutes, not 100. To change minutes into hours, divide by 60. The remainder is the minutes left over.
The minute converter
Change the minutes.
1,5 hours is 1 h 30 min (half an hour is 30 minutes), not 1 h 50 min. And 1 minute = 60 seconds.
Our time comes from the ancient Babylonians, who counted in sixties. 60 is handy: it divides neatly into halves, thirds, quarters, fifths and sixths. That is why you can’t subtract times like ordinary numbers.
Read a bus timetable
The Garden Route bus
Read the timetable and choose the answer.
Correct: 0Check yourself
- 24-hour time: after 12:00 subtract 12 for ordinary time.
- How long? Jump to the next hour, then whole hours, then the minutes.
- An hour has 60 minutes: 1,5 h = 1 h 30 min.
- Minutes to hours: divide by 60; the remainder is minutes.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 4 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Measurement9 pages · PDFPaperMemo
Ready for more? The Grade 5 time quiz gives you new questions every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Let your child work out the time for a trip or a TV show: “We leave at 14:35 and arrive at 16:10. How long do we drive?”
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 5 Maths. Always check your teacher’s notes and textbook too.