Lesson objective: Understand that an expression is a way to list out mathematical calculations, and has a specific order in which it must be evaluated.

Students bring prior knowledge of multi-step problem solving with all four operations from 4.OA.A.3, 5.NBT.B.5 and 5.NBT.B.6. This prior knowledge is extended by taking their calculations and putting them into the form of a numerical expression that can be evaluated. A conceptual challenge students may encounter is how to translate real-life or mathematical situations into numerical expressions, and how to evaluate them correctly using the order of operations.

The concept is developed through work with a tape diagram, which helps students visualize amounts that equal a specific total.

This work helps students deepen their understanding of equivalence because multiple expressions can represent the same numerical value.

Students engage in Mathematical Practice 1 (make sense of problems and perservere in solving them) as they look for entry points to solve this task, model their thinking in many ways, and continue to analyze the task within the given parameters until they have reached the specific value they are asked to calculate.

**Key vocabulary:**

- calculation
- equation
- numerical expression
- order of operations
- result
- tape diagram

**Special materials needed:**

- colored pencils if desired for coloring in tape diagrams
- graph paper if desired for creating tape diagrams