The purpose of this lesson is to move toward a general method for solving linear equations. In the Warm-up, students solve equations mentally, including equations with negative coefficients, prompting a discussion of multiplying or dividing each side of an equation by a negative number. Next, students encounter several different structures of equations, and take turns suggesting moves for solving them. They apply their growing fluency with solving equations to explain the reasoning behind a number puzzle.

As students explain their reasoning for choosing a particular move when solving an equation and listen to the choices of their partner, they must explain and critique their arguments (MP3).

The title of this lesson includes the term “linear equation.” In this course, the term “linear equation” is introduced in a later unit. It is not necessary to explain the structure of a linear equation or the differences between linear and nonlinear equations at this time.