I have some real jingle bells for kids to look at, but also found a good image of colored bells on Oriental Trading Company's website. Blown up on the Smartboard, they are a vibrant reference with highlights and shadows. Students have worked with oil pastels before making tints and shades, so that part isn't new. This study also introduces the idea of using analogous colors for back shading and variety, as the bells have reflections from lights and surrounding objects.
Rather than try to sketch in the black cut-out spaces, I find it easier to color the bell as a sphere, with several layers of oil pastel, creating the highlights and shading. This can either be a short task or a long, thoughtful one, depending on the observation skills of your kids!! Once the sphere looks "real" it is just a matter of drawing the black spaces in with the black oil pastel.
Happy Thanksgiving to all!!!