**Lesson Objective: **Practice verifying that a proportional relationship between quantities exists and writing equations that represent those relationships.

This lesson builds on students’ work with unit rate and equations. Students are presented with a table showing data from the annual school field trip. Students investigate whether the cost per student remains constant over time, and then write an equation that could be used to find the cost of the trip for any number of students.

Students engage in Mathematical Practice 3 (Construct viable arguments and critique the reasoning of others) as they debate which equation correctly represents the relationship between the number of players and the number of coaches, and again as they debate how to alter the equation if 2 coaches are hired per team. They also develop MP7, as they interpret the structure of equations.