Lesson objective: Understand that we can use the same operation on both sides of an equation to solve.

Students bring prior knowledge of solving 1-step equations from 6.EEB.7. This prior knowledge is extended to multi-step equations as students solve for a missing value in an equation of the type px+q=r. A conceptual challenge students may encounter is thinking that the equations we encounter always just use one operation, since that is what they studied in 6th grade.

The concept is developed through work with tape diagrams, which help students see how performing the same operation on both sides of an equation preserves the equality.

This work helps students deepen their understanding of operation because when you perform the same operation to both sides of an equation, the equality is preserved.

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they write and solve a 1-variable equation to model a real-world problem.

**Key vocabulary:**

- equivalent equations
- tape diagram