Why do this problem?
This problem presents learners with a pleasant and familiar
situation in which to explore aspects of the four operations. It
also relies on finding all possibilities so can be used to focus
on working systematically.
Possible approach
It might be helpful just to have the image displayed, or for
you to redraw a similar image, and for you to ask the questions
orally rather than children having to read from the screen.
Begin with Rosie and suggest children work in pairs to find
possible solutions. After a minute or so, you might like to
take a couple of answers and then emphasise you'd like to know
all the combinations
that Rosie could have bought. In a mini-plenary invite learners
to share different ways of going about finding them all and
draw attention to those who have developed a system, for
example starting with the most expensive sweet (a lollypop) and
seeing what could be bought with that; then looking at the next
most expensive (the Choco bar) and finding the combinations
which could go with it etc. At this stage, you may also want to
highlight some good ways of recording that children have come
up with.
Once you have explained about the other four children, you
could jot a reminder of how they each spent their $20$p on the
board and leave the class to explore possibilities this time.
When you bring their ideas together, you may want to praise
those who have developed systematic ways of working based on
the earlier discussions and those who explain their reasoning
clearly.
Key questions
Could all the sweets be the same?
What else could Rosie have bought if she bought a
lollypop/Choco bar/chew/mini egg?
How much do two of those cost? What about three of them? And
four?
How do you know you have all the possibilities?
Possible extension
Learners could investigate how other
amounts of money perhaps between $10$p and $20$p, could be spent
exactly.
Possible support
It could be useful for children to have
objects to represent the sweets, for example coloured counters.