Odd and Even
If we draw numbers arranged in twos you can see if they are odd or even. These numbers are even. You can see they are even across the top.

These numbers are odd. You can see they have an odd square sticking out at the top.

I am going to add two even numbers, 8 and 4. This means I am going to put them together. I have also turned them round so they fit in better.
Is the answer odd or even?

What about these two? Is the answer odd or even?
Can you write down the numbers which have been added?

Now I am going to add an odd number to an even number.
Is the answer odd or even?
Can you write down the numbers which have been added?

What about these two?
Is the answer odd or even?
Can you write down the numbers which have been added?

Finally, I am going to look and see what happens when I add two odd numbers.
Is the answer odd or even?
Can you write down the numbers which have been added?

What about these two?
Is the answer odd or even?
Can you write down the numbers which have been added?

I had to turn the pictures round so they fitted. Have go yourself.
You can cut the shapes out of squared paper or use this sheet.