Lesson objective: Understand the commutative property of addition.

Students bring prior knowledge of addition and solving word problems from K.OA.A.2. This prior knowledge is extended to the commutative property of addition as students develop strategies to add and subtract. A conceptual challenge students may encounter is understanding that they have do not have to count to add every time.

The concept is developed through work with playing cards and connecting cubes, which allows students to see that the order of addends doesn't change the total.

This work helps students deepen their understanding of equivalence because the equal sign means that quantities on both sides of the equation have the same value.

Students engage in Mathematical Practice 3 (Construct viable arguments and critique the reasoning of others) as they analyze, discuss, and prove strategies other students used to solve equations.

**Key vocabulary:**

- addends
- addition
- commutative property of addition
- equal
- equation
- sum
- total

**Special materials needed:**