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Three Ball Line Up
Two children are playing with three balls, one blue, one red and one green.
They toss up the balls, which run down a slope so that they land in a row of three.
How many different ways could the balls land?
You might like to use the interactivity below to explore the problem.
Full Screen Version
This text is usually replaced by the Flash movie.
Why do this problem?
This problem is a good context in which to encourage learners to work systematically and to be able to convince someone else that they have found all the possibilities.
The interactivity will help children to get a feel for the problem.
Key questions
If red landed in the middle, how could the blue and green fall?
Where else could red land if it wasn't in the middle?
Can you use this idea to find all the ways?
How will you remember the ways you have found so far?
Possible extension
Encourage children to use four balls/counters.
Possible support
Pupils would benefit from having three differently-coloured counters to use while tackling this problem.