Classroom Auction Project: Reverse Glass Painting

Reverse glass painting refers to glass art which is painted on one side and displayed to be viewed through the opposite side. Lampshades are one example of an object that lends itself to this technique. I have used this approach to create class murals displayed by hanging in windows.
These are the steps I took from start to finish- Any theme or design would work.

Theme: Native animals in Canadian and Pacific NW habitat.
I used plastic animals as models and let students sketch moose, elk, bear, dear, etc., on individual sheets of paper.
Students then referred to reference books to draw images of mountains, lakes etc., native to this area.
As a group, the students trimmed and arranged their individual drawings on an huge sheet of butcher paper. More background detail was sketched on the butcher paper in order to unify the mural.
I picked up a sheet of Plexiglas at a local hardware store and drilled two holes in the upper corners to thread chains through for installation. I covered those holes with tape so that they wouldn't become filled with paint.
The Plexiglas was placed over the butcher paper sketch.
First, the contour shapes were outlined in permanent marker. Then using acrylic paint, the participants painted in their images. (Bears, wolves etc., )
It was difficult for them to understand the concept that the first area painted is what is seen and that the last marks made (which are visible on the painted side) Could be hidden on the reverse side. So, if an animal is painted and then eyes are painted on top of a layer of fur, the eyes won't show on the reverse side.
If areas such as eyes and facial features are lost, they can be reclaimed by scratching out the area after the paint is dry and then repainting it. Trying to wipe it out while wet may lead to a smeary mess.
After the animals were finished, the background was painted. When the entire painting was complete, a coat of light paint was applied to the back of the entire painted surface. This enhanced the image and avoided the 'washed out' look.
Chains were strung through the back and the mural was hung in the art room window.
If you do an Internet search "reverse glass painting" you will find folk art, museum pieces, furniture and many possible ways to use this technique on different objects to make a classroom art item for an auction.

These are the basic instructions for reverse glass painting:
I used the same side for both the permanent marker lines and paint, so that the viewing side of the mural could be periodically cleaned. However, the caution in the following instructions about wearing down the marker lines with paint holds true.
http://www.ehow.com/how_2248883_make-reverse-glass-painting.html