This week the focus was to teach the students how to switch mind set between checking 2D shapes and 3D forms to help them catch mistakes and gesture relationships in their drawing.
With the middle form break down image, I am trying to illustrate that there are gestures to the way the planes of the body "Flow" together (middle right). After the stage of laying in the big shapes in simple forms, I start to break the body into planes that reinforce both the gesture and the perspective of the body. You can see how the box of the ribcage flow into the bottom of the pelvis area and how the corner of the pelvis bone flairs out to create a gesture flow to the legs.
Planes of the body is never mechanical and always have a gesture, off center apex or slight twist to the form. The gesture of the form always relates to the other body parts that are before and after it.
You can find similar information on these flow or abstraction break down from Frank Reilly's teachings. You can find some information from his notes here:
I do not start my drawings with the chart, it often over complicates things and makes the drawing flat or over stylized.
I like to use it as a "tool" on a case by case basis, if it happens to helps me organize my details to push weight, gesture or form.