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Two Clocks

Stage: 2 Challenge Level: Challenge Level:2 Challenge Level:2

This problem could be worked on in a group of about four. For more details about how you might go about doing this, please read the Teachers' Notes.

Sam and Julie are friends. Both of them have rather odd clocks at home.
In Sam's bedroom there is an old alarm clock which his Dad had thrown out because it had lost its minute hand. Although it has only its small hand, Sam can still tell the time using it. He can tell the hour, such as midday. He can tell when it is time to get up, time to go to school and time to turn his light out at night.

four clock faces with only hour hands

Which clock is showing it is midday?
At what time does Sam get up?
At what time does Sam go to school?
At what time is Sam supposed to turn out his light?

In Julie's hall there is a very old clock which lost its hour hand a long time ago.

grandfather clock with minute hand at 25 past



School finishes at half past three and it takes Julie at least half an hour to get home. Sometimes she goes to the shop on the way, and sometimes she leaves school a bit later. When she first gets home Julie always looks at the clock in the hall to see what time it is.
One week these were the times she saw:

clocks with just minute hands
On which day was it raining so she hurried straight home?
On which day did she go to the shop to buy some sweets on the way home?
On which day did she stay at school to practise in the band?
On which day did she play with Sam for about half an hour before setting off for home?
On which day did her teacher keep the class in for five minutes?

The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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