In Year 1 we have been doing a lot of work on place value and understanding tens and ones. Last week we built teen numbers using numicon, reminding ourselves that all the teen numbers have one ten in them and some extra ones.

Then we talked about how we know if a number is even or odd. We knew that for one-digit numbers, we had to be able to make groups of two from a number for it to be even, for example, 8 is even because we can make 4 groups of 2 from it.

We wanted to see if this was true for larger numbers, so tested it out with some teen numbers. We found that all even teen numbers can made into groups of 2. We also spotted that we could tell if a 2-digit number was odd or even just by looking at the ones digit. If the ones digit is an odd number, the number will be odd. If the ones digit is even, the number will be even.

We built lots of 2-digit numbers using numicon and sorted them into odds and evens.

Do you know any tricks with odd and even numbers? What happens when you add an odd number to an odd number? Or an even number to an even number?