Go here for a non-embedded dynamic worksheet.
Directions:
  1. The ratio is randomly created and plotted on the graph.
  2. Reduce the blue ratio.
  3. Use the sliders to create the ratio in simplest form. (Use the arrow keys for finer increments).Point B moves as you create the ratio.
  4. The ratio in simplest form will ALWAYS lie somewhere on the dotted line.
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