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Why do this problem?
The intention of this problem
is that learners will work together as a team. It should help in developing mathematical language as well as providing interesting practice in varied number work and possibly offer opportunities to share calculation strategies. It will probably not take a whole lesson to do.
One of these sheets needs to be printed out: this sheet (of fifteen cards) has easier questions than this second sheet (of twenty cards).
The sheets will need to be cut into separate cards. You must give out all the cards in the set you chose to do!
You can give out a set of cards to each group of four to six children. Alternatively, you can give the cards to the whole class, with some of them sharing a card. This would be more appropriate with an older age-group using the harder cards. (The questions asked in the set of cards do vary in difficulty so you may like to give specific cards to some pupils.)
To begin with, give learners time to work individually on the questions on their own cards. After a suitable period of time, encourage them to ask each other about the questions and answers on other cards. At this stage, members of the group can help each other with the questions, but discourage them from simply giving someone else an answer.
Challenge each group, or the class, to organise or arrange the cards in some way. At this point, stand back and try not to intervene as they work together. You could invite them to display their cards in their chosen arrangement and then give some time for everyone to move around the room to look at the way each group has sorted the cards. Natural leaders will probably emerge if the whole
class is using the same set!
A short plenary should provide an opportunity for the groups to explain the organisation they chose and for such remarks as "I knew my answer was wrong when it didn't fit in with anyone else's".
Tell me about the number you have found.
Have you asked others about the numbers they have found?
Did you notice anything?
Are you sure that answer is correct? Have you checked it?
Can you think of a way of organising the information you have?
Learners who find these questions easy may not have solved the problem! How can the cards be organised, arranged; or ordered? Such pupils could help other members of the team check all the answers. Some learners may want to devise their own set of cards to be used in a similar way.
You can purposely give certain cards to certain children if you do not want to take them too far out of their comfort zone where the calculation is concerned. It may be appropriate for one group of children to work using the cards in this version
of the problem. The principles are exactly the same, but the calculations involve addition and
subtraction up to $25$.