Using the graph of a line with two indicated points students collect
data on the names of the points, the rise, the run. Then students use
the rise and run to describe the slope of the line. Finally students are
asked to study the coordinates to notice how they can use the coordinates to calculate the rise and run. This should lead the students to their own discovery of the slope formula.
The visual approach helps students make sense of slope because they can visually see the slope on the grid.