In my course mastering the art of the portrait we've been talking about how to get a likeness and this is the third part if you haven't seen the other two go back and watch him they've got a lot of great information I wanted to start out with a quote from David Jamison a great drawing teacher it's it's really worth listening to what he has to say. He says and I quote "modeling form is a task of organizing values as well as recording their shapes and positions. "The first requires a careful arrangement of the forms we see–their shapes sizes and positions, and then a careful comparison of their relative values." So one of the main tasks we have to do we've been talking about in the previous segment is plumb lines - to find the tilt with the twist of the head to measure placement of things we've talked about enveloping the head in an envelope drawing from general to specific from the outside in we've talked about citing angles lots of important stuff. So today we're going to talk about modeling form and so to do that we have to learn to make crucial value distinctions; so for that we need to understand value and its relationship to form and how light reveals form because structure needs light to reveal it. For more on this topic click on the video tutorial.