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  • Subject Area

    • Math: Algebra I: Linear Functions
    • Math: PreAlgebra: Linear Functions
    • Math: PreAlgebra: Expressions
    • Math: PreAlgebra: Number Sense and Operations
    • Math: Middle Grades Math: Algebraic Thinking
    • Math: Middle Grades Math: Problem Solving

  • Author

    Texas Instruments

  • Level


  • Activity Time

    60 Minutes

  • Device
    • TI-30X IIB
    • TI-30X IIS
    • TI-34 II Explorer Plus™
  • Other Materials
      This is Activity 5 from the EXPLORATIONS Book:
      Math Investigations with the TI-30X IIS and TI-34 II: Activities for the Middle Grades

      The following materials are required for this activity:
    • Colored pencils, markers or crayons
    • Straight edge
  • Report an Issue

CDs Anyone?

Activity Overview

Students write rules for real world functions. They make a table to compare function values and graph linear functions on the coordinate plane.

Before the Activity

  • See the attached PDF file for detailed instructions for this activity
  • Print pages 40 - 45 from the attached PDF file for your class
  • Study the calculator keystrokes
  • During the Activity

    Distribute the pages to the class.

    Follow the activity procedures:

  • Write function rules for each company's discount plan
  • Calculate the cost of buying 1 through 15 of CDs from each company
  • Tabulate the results
  • Plot a graph of Cost of CDs versus Number of CDs
  • Analyze the graph and determine which company has the best plan and under which condition
  • After the Activity

    Students complete the Student Activity pages and answer questions.

  • Review student results
  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary