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Instructor Overview

Students analyze the graph of a proportional relationship in order to find the approximate constant of proportionality, to write the related formula, and to create a table of values that lie on the graph.

Key Concepts

  • The constant of proportionality determines the steepness of the straight-line graph that represents a proportional relationship. The steeper the line is, the greater the constant of proportionality.
  • On the graph of a proportional relationship, the constant of proportionality is the constant ratio of y to x, or the slope of the line.
  • A proportional relationship can be represented in different ways: a ratio table, a graph of a straight line through the origin, or an equation of the form y = kx, where k is the constant of proportionality.

Goals and Learning Objectives

  • Identify the constant of proportionality from a graph that represents a proportional relationship.
  • Write a formula for a graph that represents a proportional relationship.
  • Make a table for a graph that represents a proportional relationship.
  • Relate the constant of proportionality to the steepness of a graph that represents a proportional relationship (i.e., the steeper the line is, the greater the constant of proportionality).