(Updated: 1 Jun 2012)
An example of graphing the quadratic function [math] for -2 ≤ x ≤ 5 using the applet at http://www.geogebratube.org/material/show/id/10000
See another example of graphing y = sin x for 0° ≤ x ≤ 360° at http://www.geogebratube.org/student/m10002
Anthony Or. Education Bureau, Hong Kong.