Age 7 to 11
Why do this problem?
This problem supports children in calculating with money, while it also requires them to be systematic.
Playing with the problem for a few minutes and thinking about what the minimum price of the chocolate bar could be is a useful starting point. How can pupils convince each other that they have all the solutions? Although simultaneous equations seem to be appropriate they would just get in the way!
Try with a few different amounts of money for the two children. Does this help you to solve the problem?
What is the least the chocolate bar could be?
How much does this mean each child would have?
Are there any more answers and how do you know?
Pupils could create their own challenge along similar lines. You could give them the price of the chocolate bar and they have to create the 'clues' so that it can be worked out.
You could suggest that learners try to record what they have tried in an organised way e.g. using a list or table.