A number which is divisible by 2 and generates a remainder of 0 is called an even number. An odd number is a number which is not divisible by 2. The remainder in the case of an odd number is always “1”. The property by which we classify an integer in math as even or odd is also known as parity.

Besides counting in ones and steps of different size, one of the first properties of number that children are introduced to is that of ‘odd’ and ‘even’. This is often introduced as an extension of counting in twos from zero and one. Practical resources or pairing up groups of children can be used to demonstrate divisibility by two.

Once children can recognise odd and even numbers they can start to consider some of the properties of combining these numbers in different ways.What happens when two even numbers are added? Two odd numbers? An odd and an even number? Exploration of subtraction of odd and even numbers will reveal the pattern in their differences.