Here is an activity for students to learn about what the discriminant can tell you about a quadratic function. Here is the file you need to complete the activity:

Discriminant

Use sliders a,b and c to determine the discriminant. You will also discover the relationship between the value of the discriminant and the solutions to a quadratic.

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

Nicholas F. Bennett, Created with GeoGebra