Lesson objective: Decomposing whole numbers to determine if they are even or odd.

This lesson helps to build fluency with identifying even and odd whole numbers. Decomposing each whole number into two groups is used here as a strategy for determining even and odd numbers because it supports the definition of an even, whole number. This work develops students' understanding that an even number can be decomposed into two equal addends (doubles facts) while an odd number cannot.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they decompose whole numbers into two groups to determine if a number is even or odd. By drawing each number out as a set of items, students will work to decompose each number into two equal groups to make the claim that a number is even or to claim that a number is odd if it cannot be divided into two equal groups.

**Key vocabulary:**

- addend
- decompose
- even
- odd

**Special materials needed:**

- connecting cubes or counters (if students want to model the numbers before drawing)