|Use the mouse to drag "beads" along a graph and observe what happens to the secant line as they come together.|
This was written in JAVA, but even if you don't have JAVA installed you can just click below to
Note: This option does not require any plugin and should work on smartphones as well as computers.
Note: Many browsers no longer support Java directly but if you want to see how the applet looks in Java, then one option is to use Internet Explorer or another browser like Chrome with the IETab plugin
Or you can just use this link to [Download the App] and run it outside your browser.
Note to Students and Teachers:
This applet illustrates how the definition of the derivative of a function actually determines the slope of a tangent line.