A note on stick drawing (and no, I don't mean stick figures!): because the stick tapers at the end, it becomes more & more flexible. As you draw, the charcoal sometimes "catches" or gets a bit stuck on the paper & you can see the tip of the stick bend. Then it springs back & you get a "creative" line that you hadn't planned on, which adds to the spontaneity of the piece. Art is all about the balance between our intentions & the "happy accidents" that happen along the way.