Lesson objective: Add four two-digit addends.

This lesson helps to build procedural skill with adding four two-digit addends. Students select the addition strategies used here because they are applying known strategies to solve problems as they see appropriate. This work develops students' understanding that the sum of an addition problem remains the same no matter what strategy is used to solve it.

Students engage in Mathematical Practice 8 (Look for and express regularity in repeated reasoning) as they use strategies they have practiced in addition equations with two addends and apply them to equations with four addends.

**Key vocabulary:**

- addend

**Special materials needed:**

- 2 number cubes
- Recording Sheet