When teaching your child how to count, when he knows how to count from 1 to 9, you can start teaching him the first operations: the sum (as seen in a previous article) and now the subtraction.
To teach a young child the subtraction, take identical objects such as small rocks, seashells, pebbles….
In a Montessori class, we use golden pearls that each represents a unit.
Tell your child that you are going to teach him a new operation called the subtraction. This operation consists in taking away, in withdrawing, in removing.
Write down on paper a few easy subtractions, with the “minus” sign written in red because that sign is new to the child.
You write, for example: 5 – 3 =
Tell him that we are going to take 5 pearls, or 5 small rocks, or 5 seashells. Put the objects in front of the child aligned horizontally. Show him the “minus” sign and tell him that the sign means that we are going to remove. Show him number “3” and tell him that we are going to remove “3”. Then, take 3 objects away.
Tell the child that the result of the subtraction is what is in front of him, and count the remaining objects “1”, “2”. There are “2” left. In conclusion, “5 minus 3 equals 2” or the difference between 5 and 3 equals to 2. Once more, it is important to insist on the right vocabulary and this is a good time to introduce the words: subtraction, difference and the “minus” sign.
Then write another subtraction like for example: 9 – 5 =, and then 7 – 4 =, and so on…
This lesson can be done at a very early age (as soon as three years of age). If your child is older and can read, it is important to have him resolve small problems which involve this operation:
I have six little pieces of bread in my hand, if I eat two, how many do I have left?
The white hen has three chicks, the red hen has six chicks. What is the difference between the number of chicks between the two hens?
Your child now knows the sum and the subtraction…
Sylvie Rousseau d’Esclaibes