Done as part of a 30 minute class.
My current goal is: Reduce stiffness and make my drawings feel more dynamic, energetic, fluid
I think the headshapes are good and you are getting the angles! Maybe try 'drawing through' to construct the 'ball' of hte skull and attach the jawbone, so to speak? A little underdrawing/underlying structure lines can go a long way toward making things come out looking just right! This video is from my favorite figure artist and probably shows better than I can exactly what I mean with underdrawing
That is a very marvelous job you have created, SINE, nonetheless, I've got one tinier request: Why don't you loosen up your expressions and faces, pretty, pretty, pretty, pretty, pretty, pretty please, please, please, please, please, please?????? The thing about that is, your faces and craniums will become even more than more looser, larger, and livelier in your next class session. Hope and recite that it'll really and completely work out just for you and me.