Planes on a Head Study

I worked with soft and hard charcoal today in my drawing class to study the planes of head. My notes and scribbles are around the initial drawing. I had to remind myself not to draw dark lines but instead fill in the drawing with the appropriate values.
Always establish the darkest value first and then compare. I was reminded to keep the whites purse white.
I need to determine the highest point of the head and how it is related to the other parts of the face.
I need to be sure to make the back of the skull large enough.
I liked this exercise because it forced me to look at the shapes.
Good study.