2.OA.C.3
Pair things up to test odd or even, and write an even number as a double.
Worksheets for this standard 2 topics
The standard, officially
Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends.