The project we are working on was inspired by a project I found on the art blog Make It... a Wonderful Life.
I introduced students to the Hubble telescope, it's history, and what it does. We looked at a number of photos from the Hubble website and we talked about how many of the images looked abstract in nature. Kids saw different things in the pics like we do when looking at clouds in the sky. I pointed out how some formations looked 3d due to the presence of light and dark on them.
Like Make It... a Wonderful Life, I demonstrated how to work the pastels in a variety of ways. As students worked on their own creations, I worked on a drawing in the back of the room on a vertical easel, so students could see how I was handling things. I left the technique demo up on my projector screen, to serve as a visual reminder, too.