Odd/Even

In math workshop we are learning about odd and even numbers.
We used our rekenreks to determine if a number was even or odd.  If the top and bottom could match up with no leftovers, the number is even.  If the top and bottom have a leftover after matching up, the number is odd.  Can you tell which of these is even or odd?

We kept track of numbers that we tested.

Do you see a pattern?