These are going to be great works. Here's the outline for the lesson below.
1.) Offer up a selection of really cool photographs or illustrations of architecture. I've chosen a stave church in Norway with a rainbow, the Notre Dame illustration with a colored glass window, Icelandic turf-houses with colorful botanical roofs, the Taj Mahal in a sunrise or sunset (for advanced folk), a lighthouse by the sea, and a black church beneath a sky of aurora borealis.
Refer to the tracings when you go to draw shapes on your gray paper. Use the triangles, squares, and circles your found in your study to layout your final drawing with value.
2.) Have your student build their confidence by tracing geometric shapes: simple triangles, every variation on a square, and circles.
3.) Either vote on one of the works for everyone to do themselves on a gray piece of paper with white and black pencil OR stick with the works the students have chosen individually (depending on their excitement.)

Street-lamp, Giacomo Balla, 1909
4.) Add highlights and shadows using the black and white colored pencil.
5.) Refer to our color studies here to get an idea about how to apply the oil pastel.
6.) Apply color in the futurist way that Giacomo Balla did in 1909. Think, little birds and boomerangs all radiating out from a central light-source. All of this on top of a black and white value study drawing.
7.) Add details using the toothpicks we used to carve out highlights in our oil pastel study.
Use purple and yellow for the Taj Mahal on peach or pink paper. Alternatively, use the oil pastel for the background.
When I finish my turf-houses, I'll post their colorful garden rooftops lighting up the gray, black, and white atmosphere.