Subtraction Strip Board (presentation one)

What is the Montessori Subtraction Strip Board?

The Subtraction Strip Board is a rectangular board divided into 18 squares from left to right and 11 squares from top to bottom. There are numbers from 1 - 18 above the squares (1-9 in blue and 10-18 in red) There is a blue line dividing the board vertically after the 9th square.

There are two sets of wooden number strips from 1-9 (one set in blue and one in red) They strips vary in length from the shortest 1-strip to the longest 9-strip.

We use natural wood strips to cover the section of the board, that is not needed for the sum, we also need the Subtraction Series 1/2/3 sum cards, as well as the whiteboard marker and cloth.

How is the first presentation with the Subtraction Strip Board presented?

This activity reinforces subtraction and shows the child a different way of subtracting numbers using different materials. The child is encouraged to find the difference between two quantities using the Subtraction Strip Board and recording the answer.

The directress begins the activity by asking the child to build the blue stair on the left-hand side of the board, while she builds the red stair on the right-hand side of the board. She reminds the child that they will only be working with numbers 1 - 9, so we need to place the wooden strip over 10 - 18.

She takes the number 9-blue strip and places it in the first row, she asks the child what the number is, he should say “nine”. She then takes the number 8-strip and asks the child what the number is, the child should say “eight”. The directress places it below the number 9-strip on the board, and asks the child ‘how many more from 8 do we need to make 9’? The child then counts the remaining strips and says ‘one’. The directress takes the number 1 red strip and places it next to the number 8-strip.

For this activity, the directress leaves the strips on the board. She continues in the same manner by taking the number 7-blue strip and placing it below the number 8-strip. She asks the child ‘how many red strips do we need to make nine'? The child should then say ‘two’ and place the number 2-red strip next to the number 7-blue strip.

The directress continues in the same manner until all of the bonds of nine have been completed. She then brings out the Subtraction Series one sum card and reads the first sum to the child (9-9=) The directress reminds the child what subtraction means and she encourages the child to look at the bottom row of the board as they will be taking the number red-9 strip away, the answer will be zero as there is nothing left in that row.

She reads the next sum to the child (9-8=) the directress reminds the child they need to take 8 away from 9, she takes the number 8-red strip away at the bottom of the board and asks the child to count what is left, the child should then say ‘one’. The directress reminds the child how to write the answers in the block provided on the sum card. The strips are always replaced back into the stair. The child continues in the same manner until all of the operations on the card have been completed.

What does the child learn by doing the first presentation with the Subtraction Strip Board?

This activity gives the child further practice with subtraction, it shows the child different ways of doing subtraction and it reinforces the concept of subtraction and the minus (-) and equal (=) signs.

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.