Education Technology

Algebra I: Linear Inequalities in One and Two Variables: Rays and Half Planes

by Texas Instruments


  • Students will relate inequalities in one variable (on a number line) to inequalities in two variables (on the coordinate plane).
  • Students will also identify possible solutions to inequalities in one and two variables, and recognize the pattern in the coordinates of the solutions.
  • Students will graph linear inequalities with vertical and horizontal boundary lines.


  • boundary lines
  • coordinate plane

About the Lesson

This lesson introduces linear inequalities with vertical and horizontal boundary lines by relating them to simple inequalities on the number line. Inclusive and non-inclusive inequalities are explored by relating dotted and solid boundary lines in the coordinate plane to open and closed circles on the number line. This activity can lead into graphing linear inequalities with boundary lines.