In this lesson, students examine graphs to describe the situation and then examine other graphs to describe what is wrong with them. In particular, students must determine reasonable domains and ranges for situations to see that the graphs match what is expected. In the associated Algebra 1 lesson, students describe the entire domain and range for functions based on the situations and graphs. Students are supported by examining pieces of the domain and range and then inventing their own graphs.

To describe a feasible situation based on a graph and recognize errors in a graph, students need to reason abstractly and quantitatively (MP2). Students model with mathematics when figuring out the ways a graph does not fit the situation it is representing (MP4).