Lesson 14

In previous lessons students have started to acquire fluency with a general method of solving equations, and have seen that different solution paths are possible. In this lesson students learn to stop and think ahead strategically before plunging into a solution method. After a warm-up in which they construct their own equation to solve a problem, they look at equations with different structures and decide whether the solution will be positive, negative, or zero, without solving the equation. They judge which equations are likely to be easy to solve and which are likely to be difficult. 

When students look for features of an equation that will tell them something about the solution or help them choose a solution path, they engage in MP7.

Students may notice the term “linear equations” in this lesson, which is one they will not be formally introduced to in this course until a later unit due to how certain lessons are rearranged. Let students know that the equations they are working with in this lesson and the previous few lessons are all types of linear equations and that they will learn more about what makes an equation linear or nonlinear in future units. Students will work directly with linear equations in the next unit and consider nonlinear equations in a later unit, so it is not necessary to give a detailed explanation at this time.