Lesson objective: Understand that equivalent expressions always have the same value.

Students bring prior knowledge of equivalent expressions from 6.EE.A.3 and 6.EE.A.4. This prior knowledge is extended to expressions that include rational numbers as students identify more complicated equivalent expressions. A conceptual challenge students may encounter is thinking that the apperance of rational numbers will change when expressions are equivalent.

The concept is developed through work with expressions, which allows students to experiment with the expressions and justifying why two expressions are equivalent.

This work helps students deepen their understanding of operations because we can use the properties of operations to generate equivalent expressions.

Students engage in Mathematical Practice 3 (construct viable arguments) as they justify their choices for which expressions are equivalent

**Key vocabulary:**

- equivalent expressions
- rational number
- substitute
- variable

**Special materials needed:**

- expressions cards printed from task slide (optional)