Look at these four towers of cubes: one is 3 high, one is 5, one is 2, and one is 6. They belong to four friends.
If the four friends shared all their cubes fairly, so everyone had the same, how many would each one get?
Watch what happens when we make the four towers the same height. We move cubes off the tall towers and put them onto the short ones, taking care not to add or lose any.
When every tower is level, that even height is the fair share for everyone. We call this fair share the mean.
There is also a quicker way to reach the same answer: add all the heights together, then share the total between the towers.
We level each set of towers together, one set at a time. Watch the pupil at the board move the cubes, then read off the fair share with them.
For each set, we move cubes from the tall towers to the short ones until they are all the same, then read off the even height.
Here is the add-then-share method written out for the four friends' towers, so you can see each step clearly before you use it on your own.
In your maths copy, draw three towers from the heights the teacher gives you. Then write the total of the three heights, and underneath write the fair share.
Remember: add the heights first, then share the total between the number of towers, just like the working we have just seen.
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