Note to Students and Teachers:
This applet gives practice in estimating the slope and y-intercept of the line through two points.
Being able to quickly estimate such slopes 'by eye' is a basic but important  and useful skill for the study and application of calculus. The applet gives you a hint if you need it, and the option of using the slider to control the slope value lets you work by trial and error at first; but the goal should be to be able to just type in good approximate values on your first guess.

Note to Developers: The link provided above is to a version that should run in most browsers.
A new version built with the new GeX component library is also available - but with no real advantages aside from its simpler code. In fact the overhead of working in terms of well defined and flexible components sometimes slows things down a bit, and examples like this serve as a testbed for maintaining the efficiency of the component-built applets.