Group operations: Dynamic subtraction (with change)

How this activity is presented

This activity is very similar to Static subtraction, but this time exchanging will be taking place. The directress can either present this in groups or individually like before.

She begins by asking the children to lay out the small and large number cards each on separate mats and the golden beads on another mat. The directress tells the children that they will be subtracting the smaller number away from the larger number to get an answer. The larger number is made up from the large number cards, for example, 1432 and is placed on the child’s tray, he then is asked to go to the banker to collect the corresponding beads for that number. This is called the ‘minuend’ in Montessori Maths.

The directress makes up a smaller number, for example, 1114 from the small number cards. This is called the ‘subtrahend’ in Montessori maths. The child begins to subtract four units, the directress remind him that we don’t have enough units to take away, so we can exchange one 10- bead bar for more units. The child then takes one 10-bead bar from the tens and exchanges it for 10 units. He notices that there are now enough units to take four away.

The child repeats in the same manner with the tens, hundreds, and thousands, exchanging if necessary. The answer is made up of the small number cards. The directress assists the child in packing away and continuing to do more sums if he would like to.

Looking for more Montessori activities?

Here is a list of all the Montessori Maths activities including Early Maths, Introduction to the Decimal System, Seguin Boards, The Hundred Board, The Short Bead Stair, Bead Chains, The Snake Game, Group Operations, The Large Number Rods, Recording with the Small Number Rods, The Short Bead Stair, The Strip Boards, The Boards, The Stamp Game, The Abacus, The Dot Game, and Fractions. Just click on the page you want to learn about to go there.

Early Maths

Introduction to the Decimal System

The Short Bead Stair

The Short Bead Stair: orientation exercise

Seguin Boards

The Hundred Board

The Hundred Board

Bead Chains

The Snake Game

Group Operations

Large Number Rods

Recording with the Small Number Rods

Recording with the Small Number Rods