Lesson objective: Solve problems using the relationship between variables.

This lesson provides an opportunity for students to apply their knowledge and understanding of ratio relationships to a real-life situation. Students are asked to determine which of four companies Mr. Lee ordered pencils from based on a verbal description, a tabular description, an equation and a graph and justify their conclusion.

Key Concept students will use:

- We can use relationships between variables to find missing values in a data set.

Skills students will use:

- writing equations to model the relationship between two variables.
- identifying the relationship between variables based on information in a table.
- identifying the relationship between variables based on information in a graph.

Students engage in Mathematical Practice 8 (look for and express regularity in repeated reasoning) as they use the proportional relationship between variables to find unknown values in the relationship. Information will be presented in tables, graphs and verbal descriptions and students will need to write an equation or apply scaling techniques to determine if a given data point belongs to each set.

**Key vocabulary: **

- dependent variable
- equation
- independent variable
- ratio relationship
- scaling