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
This investigation explores using different shapes as the hands of
the clock. What things occur as the the hands move.
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?
Well done to everyone who sent in solutions for this one. The
following people managed to have the correct leaving times for both
of the riders as well as explaining how they worked it out:
Ben (Yarm Primary
School, Stockton on Tees)
Jason (Priory Middle
Jesse and Sally from Tattingstone School,
(Crofton Junior School, Kent) Excellent
The answer was explained well by Emily (Tattingstone School)
"To work out this problem all I did was find out how long it would
take them to get there and subtracted it away from the 12:00
For example, if it took Nirmala 1 hour to go 6 km, it would take
her 11/2 hours to get there because I had to add on the extra 3 km.
(I worked out that it would be 1/2 hour extra because 6 is one hour
so half of 6 is 3 and 3 would therefore be 1/2 an hour).
If she wanted to get there for noon she would have to
leave at 10:30.
I did the same to work out how long it would take for Riki to
get there. If it took him 1 hour to go 4 km it would take 2 hours
to go 8 km. He had 1 km to go and I found that it would take him an
extra 15 minutes to get there because if it takes 1/2 an hour (30
mins) to go another 1 km. So altogether it would take him 2 hours
and 15 mins to get there and he would therefore have to
leave at 9:45.
Most people did it the way described by Emily, but
School, Singapore) did it differently. He took the distance to
Market and divided it by the distance travelled in one hour. The
answer gave the number hours it would take. So....
9 000 m divided by6 000 m = 1.5 hours
9 000m divided by 4 000 m = 2.25 hours