Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.
Subject Area: Mathematics
Grade: 8
Domain-Subdomain: Expressions & Equations
Cluster: Level 2: Basic Application of Skills & Concepts
Cluster: Understand the connections between proportional relationships, lines, and linear equations. (Major Cluster) -

Clusters should not be sorted from Major to Supporting and then taught in that order. To do so would strip the coherence of the mathematical ideas and miss the opportunity to enhance the major work of the grade with the supporting clusters.

Date Adopted or Revised: 02/14
Date of Last Rating: 02/14
Status: State Board Approved
Assessed: Yes


  • Item Type(s): This benchmark may be assessed using: MS , TI item(s)

  • Assessment Limits :
    All triangles must be right triangles and on a coordinate grid. Numbers in items must be rational numbers. Functions must be linear.
  • Calculator :


  • Context :



  • Test Item #: Sample Item 1
  • Question: Select all pairs of triangles that can be used to show the slope of a line is the same anywhere along the line.



  • Difficulty: N/A
  • Type: MS: Multiselect

  • Test Item #: Sample Item 2
  • Question:

    Two collinear points are given in the table.

    Give a third point that is also on this line.


  • Difficulty: N/A
  • Type: TI: Table Item