Seeing Forms

Unlike the previous two (Seeing Values, and Seeing Shapes), this is about seeing things 3-dimenionally. 

If you are looking at a man's head that's in an angle where you'd only see his one ear, you must be able to accurately locate the other ear that's not in view. To do this, you must see things as if they are transparent. 

In this image below , let's call these wires, "formwires". This is basically the idea. You need to be able to see and draw in these formwires although you wont need to draw so many of them when you are actually drawing for the exercise. But just enough to know that everything is made of these formwires, and the outer lines you see of whatever you draw, are actually illusions of these formwires appearing in certain angles where they’d connect or if the whole form is covered with formwires they’ll fill in to become  hard surfaces . Thus when you make lines, it's important to be aware of this and make them always wrap around the form. 

Think sculpturally and be sensitive to what is coming towards you, and away from you, closer to you, and further from you. 

Keep these in mind and try this exercise (see video below) . Start out by looking at your subject in a very 3-dimensional and transparent manner with formwires, then start by sketching in lightly and roughly these formwires. Build it inside out, and as you arrive at outer lines, keep in mind that they are also formwires wrapping around the form, as aforementioned, not just outer contours. 

Fill up the sketchbook drawing this way. The more you become adept at it, you'll need to draw less and less formwires, then eventually rarely or never. Back in the days, the traditional Disney animators were masters at drawing this way, and you would see them doing rapid linear drawings without any provisional lay ins such as the formwires. But they all see the formwires without having to draw them all in.