Lesson objective: Find missing values in a data set using points on a graph.

This lesson helps to build procedural skill with finding missing values within a data set by using the relationship between the variables. Graphs are used here because they deepen students' understanding of the relationship between variables in a coordinate plane and prepare students for future work with linear equations. This work develops students' understanding that relationships between variables can be used to find missing values in a data set.

Students engage in Mathematical Practice 8 (look for and express regularity in repeated reasoning) as they identify the relationship between variables in ratio relationships. Students will use graphs and the operations of multiplication and division to find unit writes and write equations that model the given relationship. Students will then use the equation to find missing values in the relationship.

**Key vocabulary:**

- axis
- dependent variable
- factor
- independent variable
- ordered pair
- plotting points
- ratio relationship
- unit rate