Where can you draw a line on a clock face so that the numbers on both sides have the same total?
Bernard Bagnall recommends some primary school problems which use numbers from the environment around us, from clocks to house numbers.
Stuart's watch loses two minutes every hour. Adam's watch gains one minute every hour. Use the information to work out what time (the real time) they arrived at the airport.
On a digital clock showing 24 hour time, over a whole day, how many times does a 5 appear? Is it the same number for a 12 hour clock over a whole day?
Which times on a digital clock have a line of symmetry? Which look the same upside-down? You might like to try this investigation and find out!
During the third hour after midnight the hands on a clock point in the same direction (so one hand is over the top of the other). At what time, to the nearest second, does this happen?
Is it possible to rearrange the numbers 1,2......12 around a clock face in such a way that every two numbers in adjacent positions differ by any of 3, 4 or 5 hours?
These clocks have only one hand, but can you work out what time they are showing from the information?
Do you know the rhyme about ten green bottles hanging on a wall? If the first bottle fell at ten past five and the others fell down at 5 minute intervals, what time would the last bottle fall down?
On a clock the three hands - the second, minute and hour hands - are on the same axis. How often in a 24 hour day will the second hand be parallel to either of the two other hands?
These clocks have been reflected in a mirror. What times do they say?
How many times in twelve hours do the hands of a clock form a right angle? Use the interactivity to check your answers.
Use your knowledge of angles to work out how many degrees the hour and minute hands of a clock travel through in different amounts of time.
These two challenges will test your time-keeping!
Can you put these times on the clocks in order? You might like to arrange them in a circle.
Can you put these mixed-up times in order? You could arrange them in a circle.
This investigation explores using different shapes as the hands of the clock. What things occur as the the hands move.
Which segment on a digital clock is lit most each day? Which segment is lit least? Does it make any difference if it is set to 12 hours or 24 hours?