In the example above I used the Y-axis formula, y=mx+q, to enable the generation of straight lines on a bidimensional plane.

The variable m is the slope (or gradient) of a given line, while q is the y-coordinate point where Y-axis and a given line cross.

Try to change the values for both the slope and the y-intercept variables in the ranges shown and press the proper button to have straight lines generated according to what you filled in.
Lines will be created by means of a nice animation process which makes the whole application more engaging.