Slope

The slope of a line is the rate of change in the y axis divided by the rate of change in the x axis.

1. Draw Cartesian coordinate system, and draw a line that goes through points (0,0) and (1,1). What is the slope? (Change in y is 1, change in x is 1, so the slope is 1.
2. Draw a line that goes through (2,2) and (3,2). What is the slope? (Change in y is 0, change in x is 1, so the slope is 0.
3. Draw a line that goes through (2,2) and (3,1). What is the slope? (Change in y is -1, change in x is 1. Slope is -1.
4. Draw a line that goes through (-1,-1) and (-1,-2). What is the slope? (Change in y is -1, change in x is zero. The slope is -1/0 which is undefined.

Discussion topics. Is the slope for #4 infinite? Maybe it's minus infinity.