Students can drag points to modify the initial condition and the iterative function at any time, and may perform any number of iterations. This page is available in Spanish as [url]http://geogebratube.com/material/show/id/53309[/url] . There is a "YouTube" video that shows how to use this construction: [url]http://www.youtube.com/watch?v=Of7BPQfz6Jo[/url]