Lesson objective: Interpret the meaning of expressions without evaluating them.

This lesson helps to build fluency with intepreting expressions. Base ten blocks and tape diagrams are used here because they help students visualize the relationship between the expressions. This work develops students' understanding that the goal of writing a numerical expression is not always to compute an answer.

Students engage in Mathematical Practice 2 (reason abstracly and quantitatively) as they interpret the meaning of expressions without evaluating them.

**Key vocabulary:**

- compute
- evaluate
- numerical expression

**Special materials needed:**

- base ten blocks, if desired, for modeling expressions with manipulatives