## The notion of odd and even numbers

The notion of odd and even numbers is taught very early on in a Montessori school. It is a piece of material we use just after the red and blue bars, the rough numbers and the spindle box. The necessary material is that of numbers and tokens. You will see that it is something that you can easily make at home. It is made of numbers from 1 to 10 and of 55 tokens, preferably red. This material will help your child to set the numbers in order from 1 to 10 and to count the tokens associated to these numbers.

When following the chronology of the presentation of Math material in a kinder garden class, this is the first time that the child sets the numbers in order on his own.

Nonetheless, this material can be presented to a child at the age of primary class to learn the notion of odd and even numbers.

Ask the child to set the numbers horizontally from left to right, and from 1 to 10 (see photo).

Then, show the child number 1 and set one token under it. Then 2, and set 2 tokens horizontally side by side leaving a small space between the two, then 3 and set 2 tokens horizontally side by side leaving a small space between the two and the third token below in the space left by the two above tokens.

Then for number 4, set 2 tokens side by side and 2 tokens below. For number 5, set the 4 first tokens like for number 4 and the fifth token below the empty space left by the above ones. Then, ask the child to continue setting the tokens until number 10.

The error control consists in the fact that all tokens have to be set. Make sure that you have the right number of tokens (55) before you start the exercise.

Look at the way we set the tokens on the picture above as it is essential for the next part of the lesson.

First step: today, I am going to teach you the notion of odd and even. Use your finger (just like in the video) and show odd and even.

Second step: ask your child to show you an odd number and then an even number. Repeat this several times.

Third step: show him a a number and ask him “what is this number?”. Show him another number and ask the same question. Repeat this several times.

Conclusion: Today, you learned that 1, 3, 5, 7, 9 are odd numbers and 2, 4, 6, 8, 10 are even numbers.

With a young child, the lesson ends here. With a child in primary class, you continue the lesson and tell him that all numbers that end in 1, 3, 5, 7, 9 are odd numbers and all numbers that end with 0, 2, 4, 6, and 8 are even numbers. Ask him to give you some even numbers, then some odd numbers and write down numbers on a piece of paper and ask “how is that number?” Repeat this several times.

The child will keep the visual and tactile sensation of what odd and even numbers are and therefore remember them better.

Sylvie d’Esclaibes