Lesson objective: Understand that addition and subtraction can be used to solve real-world problems.

Students bring prior knowledge of addition and subtraction from K.OA.A.1. This prior knowledge is extended to real-world problems as students use objects and drawings to represent the word problem situations. A conceptual challenge students may encounter is connecting addition and subtraction.

The concept is developed through work with modeling situations using addition and subtraction, which supports students as they develop an understanding of addition and subtraction as inverse operations.

This work helps students deepen their understanding of operations because addition and subtraction are inverse operations.

Students engage in Mathematical Practice 4 (Model with mathematics) as they use manipulatives and drawings to solve problems and explain their thinking.

**Key vocabulary:**

- addition
- minus
- plus
- subtraction
- total

**Special materials needed:**

- cups or containers for students to use as vases as they act out the problem
- manipulatives, such as counters