Students will learn that a line cannot be uniquely determined by its slope, nor by a single point on the line. Slope-intercept and point-slope form both specify a line by specifying a point and a slope. In the case of slope-intercept form, the point is \((0, b).\) The two point form specifies a line by specifying two points, instead of a slope and single point. This is adequate, as any two distinct points specify a unique line. After students learn this, they'll learn what two point form is. They'll also learn why two point form cannot describe vertical lines.

Two-Point Form by MyWhyU

Next, give your students these challenges:

Conclude by leading this investigation:

Ballast – addition puzzles

by MathPickle