Anyway, before we move on to the next part of the lesson, I want you to take a look at those three layered frames up there, where I’m in-betweening the arm on the rough-sketch, moving up and out from the body. Just a reminder: the human body moves in arcs. See how I have those little notches to mark where the elbow should be, and how I may have used a straight line to measure the halfway point between…but I used an arc to measure where the elbow should be? Because of the way joints are constructed, any motion takes place along an arcing path. Don’t believe me? Move your arm, or your leg, and watch the tip of your fingers or toes. They’ll transcribe an arc, not a straight line.