Slope is the steepness of a line: the rise divided by the run between any two of its points. On a graph through the origin the slope is the unit rate, so a steeper line means a faster walker. Similar triangles show the slope is the same between any two points, which is why one equation, y = mx, fits the whole line, and y = mx + b fits a line that starts at b. The crew measures slope on a board ramp at the Puzzle Post.