Structure homework and thoughts on value

These are some really quick copy sketches from plates provided for structure figure drawing. I probably spent no more than 5 minutes on the most complex of them so don't judge ;) I just want to get a good feel for the dimensions and I'm not really all that concerned with perfect accuracy. It seems like I've seen a diagram somewhere that shows a simplified version of all the planes of the head, and I'd like to find and copy that too. Then get back to my model skull and do some quick sketches from it. And finally start trying to sketch the skull from my head from different angles and see how I do, ha. Could be a disaster, but I'm gonna try ;)

I forgot to take a picture of my long pose in progress yesterday (I bet you're so sad...). But I'm trying to sort out what I'm hearing about values. So I'm going to try to splat out my thoughts on value organization while they're fresh. And maybe I'll need to refine these thoughts later, but here goes. It's good to compress your values in either the lights or darks to unify the drawing (and by compress, I mean, simplify them the way they simplify when you squint down--push them closer to one value, with very slight variation within that one value). So you can either compress the darks, and leave more room for value variation in the lights. Or you can compress the lights, and leave more room for value variation in the darks. Another option would be to compress in both the lights and darks and rely almost entirely on the variation of line in the contour and core shadow lines to describe form (like we do in quick 2-hr figure sketches). At least that's how I'm understanding it right at this second. If you have a lot of value variation in both the lights and the darks, the drawing won't hold together and will appear spotty. So if you understand that, you can push the drawing either way based on what you want to say with it, or how close to direct observation you want to be.