This is a project my mixed high school class (Grades 10-12) completed sometime last year. I had a stack of random gold scratch art board that had been hidden in a back cupboard (you know how it goes) that I re-discovered during a Spring cleaning. I usually give a lot of options for subject matter for my high schoolers, so I simply demonstrated how to use the scratch board and told them to focus on line variety (different thicknesses), different hatching techniques, pattern and/or texture (fur, feathers, etc).
The boards came with some really dull wooden styluses- my students just instinctively knew they wouldn't be able to get the amount of desired detail with them, so constructed their own 'shanks' from taping/hot gluing a push pin to the end of a pencil.
They first drew their image on copy paper that was the same size as the boards (8 1/2 x 11"). Then they taped the paper to the boards and traced over all the pencil lines firmly using a ball point pen. This transferred the design to the scratch board. Then they scratched away.
Some Grade 10 - 12 results: