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'Practice Run' printed from https://nrich.maths.org/
Why do this
problem?
This problem could be used when time, length and distance or
doubling and halving are being introduced or discussed. It requires
careful thinking to work out how the problem should be tackled so
that doing it could lead to a useful classroom discussion.
Possible approach
This is a problem which is all too easily misread. It would
therefore be a good idea for the whole group to read it together
and then put it into their own words. These can then be compared
and a discussion started on the best place to begin doing the
problem itself.
After this learners could work on the problem in pairs so that
they are able to talk through their ideas with a partner. It would
be a good idea if squared paper were provided to encourage learners
to make a table of their findings.
At the end of the lesson the group could be brought together
again to discuss their findings and how they reached them.
Key questions
What exact measurement do we know from the question?
How far had Chandrika to go when she fell?
How might you use a table to organise the
information?
Possible extension
Learners could change the problem to ask what the
figures would be if the race was exactly $2$ kilometres long.
Possible support
For those who are struggling, you could suggest starting at the end
of the problem and working backwards.