||4 – 6 years approx.
However, the child finds that there are not enough units to take away from and so he is required to go to the bank and to exchange a ten-bead bar for 10 single units.
When the units are replaced on the operations mat, the child sees that there are now enough units to take away from.
He places 4 unit beads on his tray.
He does the same with the tens, hundreds and thousands, changing at the bank when necessary.
The small number cards are removed from the tray and placed below the large number cards.
The tray is placed to one side.
The Montessori Directress then explains that if we count the beads left on the mat we will have the answer to the subtraction sum.
The child counts, starting with the units, then tens, 100’s and 1000’s.
The child collects and places the corresponding small number cards below the beads at every stage.
The Montessori Directress re-states the sum. She also says that we did “subtraction” – that is, we started with a big amount and now we only have a small amount of beads left.
End the work cycle.