Look at these two cube towers. One is 2 red cubes joined to 9 blue cubes. The other is the same tower flipped end over end.
Did the tower get any taller when we turned it around?
Two sums on the number line. Look at where each sum starts, how many jumps are shown, and where it lands.
Now two more sums. Do they land on the same number?
Both pairs land on the same total. Nine jumps from 2 is the long way. Two jumps from 9 is the short way.
A turnaround is the same two numbers swapped, like flipping the cube tower. The total stays the same, so we stand on the bigger number and make fewer jumps.
One pupil comes to the board. We turn a sum around: stand on the bigger number and count on the smaller one.
Try 3 + 9, then 2 + 11. The class watches where they land and agrees out loud.
In your maths copy, write these two number sentences one under the other:
Now make up a turnaround pair of your own: choose any two numbers, write the sum both ways round, and check that both land on the same total.
We will turn these around together. Bigger number first: same total. For each sum, say which number is bigger. Then stand on it and count on the smaller one. Check where you land.
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