In this lesson, students examine tables that represent nonproportional relationships. They divide the pairs of values on each row to calculate the unit rate and see that the unit rates are not the same for every row. Next, they use this observation to distinguish between tables that can and cannot represent a proportional relationship.

As students look at data from a context and reason about whether it makes sense quantitatively for the data to represent a proportional relationship, they practice making viable arguments (MP3).

A note on terminology:

It is not possible to determine that a relationship is certainly proportional just from examining a table. There may be other pairs of values not shown on the table that are related by a different unit rate. Therefore, when a table shows the same unit rate for every row, we say the relationship could be proportional.

The goal of today’s exercise is to use the suggestions from the previous exercise to revise the “Norms” sections of the Math Community Chart and to invite students to reflect on one norm that will be a strength for them. Both activities begin to build shared accountability for and investment in the classroom norms.