The mathematical purpose of this lesson is for students to practice connecting written descriptions, equations, and graphs representing the same situation. In the first activity, students connect graphs of pairs of lines with related situations. In the second activity, students practice writing equations to represent a situation, then examine points on and off the pair of lines in context. In the associated Algebra 1 lesson, students continue this work and begin to solve systems of equations.

Finding connections between different representations of the same situations allows students to look for and make use of structure (MP7).