Lesson objective: Understand how to substitute a given value for a variable into an equation and evaluate to determine if that value makes the equation true.

Students bring prior knowledge of algebraic relationships from 5.OA.A. This prior knowledge is extended to equations as students substitute a given value for a variable and evaluate an equation to determine if it makes the equation true. A conceptual challenge students may encounter is understanding how to determine if the value of a variable makes an equation true.

The concept is developed through work with tape diagrams, which explain how variables follow the same arithmetic properties as numbers.

This work helps students deepen their understanding of equivalence because the value of the variable makes the equation true if the expressions on each side of the equal sign are equivalent.

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they reason which value will make an equation true. Students will then use quantitative skills to determine if a given value is a solution to the equation. Students will use qualitative skills when deciding how to represent the equation using tape diagrams or number lines.

**Key vocabulary:**

- equation
- solution
- tape diagram
- variable