Most of these works were done between 10 and 30 minutes with charcoal, although some were done with conte crayon. The class would generally start out with us doing 30 second drawings as a general exercise. For the first half of the semester we slowly built up to a 30 minute time limit. Most of these are probably 20 and 30 minute (I failed to make note), simply because the extra time allowed more rendering work. But oftentimes the more anatomically correct drawings were those done in a short amount of time when there was only time to focus on one part of the anatomy.