Lesson objective: Write an equation to prove if a number is even or odd.

This lesson helps to build fluency with recognizing equations that represent even and odd sums. Equations are used here because it supports the decomposition of whole numbers to determine if a number is even or odd. This work develops students' understanding that we can write an equation to show that an even whole number is the sum of two equal addends.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they write an equation to determine if a given whole number is even or odd.

**Key vocabulary:**

- addend
- decompose
- doubles addition fact
- doubles addition fact plus one
- even
- odd
- sum

**Special materials needed:**

- counters (optional)