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Why do this problem?

This problem would be a good one when doing calculations with fractions. It also requires logical thinking and organising of results. Different strategies and approaches can be taken: knowledge of addition, or multiples, or an understanding of fractions can be used to arrive at a solution.

Key questions

What do you think is a good way to start?
How big was Katie's balloon after the second (third, fourth etc.) puff?
How big was Will's balloon after the second (third, fourth etc.) puff?

Possible extension

Learners could make up a similar problem of their own for a friend to try.

Possible support

Breaking the problem down step by step will help learners reach a solution. It might be useful to have each subsequent piece of information written on a separate card so that they can be given to children when ready, rather than presenting all the information at once.