Illustrative Mathematics
Proportional Relationships, Lines, and Linear Equations
The resource is a good introduction to what makes a proportional relationship between two lines. Discuss the similarities of both lines and the possibility of intersection. Use this opportunity to list other acceptable forms of each...
Texas Instruments
Texas Instruments: Investigating Equations of Lines
In this activity, students explore the equations of lines written in the form: y = mx + b. They move points defining the lines, and view the related changes in the parameters of the equations.