Trapezoid to Parallelogram

We were able to construct a parallelogram out of two identical trapezoids with paper, pencil, and scissors. But can you do this without using tangable objects?
Below is a trapezoid (ABCD) that you need to transform to make a parallelogram. After you think that you have the answer check it.
Make sure your transformations pass the drag test. Also, compare the area of Trapezoid ABCD with the area of the parallelogram.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

Holly Phelps, July 24, 2008, Created with GeoGebra