Cell Phone Plans: Writing & Using Linear Functions From Real-World Scenarios

Cell Phone Plans is an 8th Grade math activity that gives students the opportunity to create and use linear equations to model real-world scenarios. This 5-page printable activity gives students four increasingly challenging scenarios in which they must create, graph, and use a linear equation based on four different cell phone plans. Once complete, they must use their knowledge of linear equations to compare the phone plans and figure out which one is the most reasonable for them.

Each of the 4 initial tasks requires student to:

• Identify or calculate the rate of change
• Identify or calculate the initial value
• Write a linear equation in the form y = mx + b
• Create a table of values
• Create an accurate graph
• Answer questions about the phone plan using their linear equation

Great as a summation activity at the end of a unit on linear functions, this differentiated activity starts students with a phone plan that gives both the rate of change and the initial value, then increases in challenge in each following task. By plan #4 they must write an equation by calculating both the initial value and rate of change using only two given data points.

Once all 4 phone plans are complete, they must compare the phone plans and determine which plan they would want to use, and why.

This lesson can be done as a whole class direct instruction lesson, as independent practice, as a partner activity, or even with whole table groups to encourage problem solving and math discussion.

This lesson includes the following materials:

• Complete lesson directions with suggestions on how to teach it in your classroom.
• 5 printable task pages (4 phone plan pages and 1 comparing plans page)
• Complete worked out solutions.

If you have been looking for a good linear functions formative assessment or team-based activity, this lesson is a great fit.