Lesson objective: Solve problems using the number line to show addition and subtraction strategies.

This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a real-life situation. Students are asked to show on the number line a correct strategy for solving the problem.

Key Concept students will use:

Skills students will use:

- place value understanding to add and subtract using a variety of strategies (Grade 3, Unit 3)
- a number line to solve many types of addition and subtraction problems (Grade 2, Unit 2)
- representations of a three-digit number as hundreds, tens, and ones, from left to right. (Grade 2, Unit 6)

Students engage in Mathematical Practice 1 (make sense of problems and persevere in solving them) as they use the number line to understand the problem and the meaning of the question. Students engage in Mathematical Practice 4 (model with mathematics) as they write number equations to describe how they used the number line.

**Key vocabulary: **

- grams
- kitchen gram scale
- number line
- pan balance

**Special materials needed:**

- kitchen gram scale
- number line for demonstration (0 to 2,000)
- pan balance scale and gram weights