Why do this problem?
This
problem fits in well with counting and skip-counting (counting
by twos etc.) and can be solved by physically modelling the
biscuits and decorations with whatever objects are convenient. It
is a good opportunity for children to choose the way they represent
the problem in order to solve it. It may also be appropriate to
introduce vocabulary such as "multiple".
Possible approach
An important element in
understanding the problem is the language of ordinal numbers, so
'warm-up' activities which involve using the concepts of first,
second, third and fourth would be worthwhile for young
children.
Invite learners to work
on the problem using whatever they find most helpful - have paper,
pens, pencils, cubes, counters etc. easily available. You may like
to stop them part way through to share some different
representations with the whole group. Some children might have made
models with differently-coloured cubes for the decorations, some
may have drawn pictures, some may have used symbols. Invite the
children to comment on the different ways of recording - what are
the advantages of each way? You may find that some learners adopt a
different representation following the discussion and it would be
interesting to know why this was.
For those children who
are more mathematically experienced, consider linking this problem
with the idea of common multiples through the multiplication tables
and the hundred square.
Key questions
Which other biscuits have
icing on?
Which biscuits have a
cherry on them as well as the third one?
What about the biscuits
with a chocolate button on them? Which ones are they?
Tell me about the
biscuits that have no decorations on them.
Possible extension
Generate your own similar
problems using a greater number of biscuits and different
combinations of skip counting, or encourage investigation of the
various possibilities. Can children find a combination of
skip-counting that allows every biscuit to be decorated?
Possible support
With practical equipment
available to model the problem, it should be accessible to most
learners.
Handouts for teachers are
available here (
word
document,
pdf
document), with the problem on one side and the notes on the
other.