The note
How schools teach it now
Schools use a time number line: jump to the next o'clock, then on in hours and minutes. Column subtraction goes wrong with times (there are 60 minutes in an hour, not 100), so number lines are preferred.
5-minute kitchen-table activity
Use a bus or train timetable: 'If we leave at 10:35 and the journey takes 1 hour 40 minutes, when do we arrive?' (12:15.) Let your child plan the timings for a day out.
Worked example
A film starts at 6:45 pm and lasts 1 hour 50 minutes. When does it end?
- Jump 15 minutes to 7:00 pm. That leaves 1 hour 35 minutes.
- Jump 1 hour to 8:00 pm.
- Jump 35 minutes to 8:35 pm.
Answer: 8:35 pm
Common mistakes to watch for
- Treating time like decimals: 1.5 hours is 1 hour 30 minutes, not 1 hour 50.
- Using column subtraction: 10:20 − 9:45 is 35 minutes, not 75.
- Forgetting that months have different numbers of days.
Encouragement
- Try saying
- “Let's jump to the next o'clock first.”
- Rather than
- “Can't you tell the time yet?”