This is my first time on Line of Action, but I was asked to give a critique before continuing into the site. That I can do. I've critiqued in two other courses, even though I am a bare beginner at Life Drawing. I have the same assignment, approximately. However, we are to use only the CSI method: arcs, s-curves, and lines. Your first sample uses that method, and so far as I can tell you have met the requirements.
I hope people with more experience at gesture drawing can give you more help.
Now I'm going on to find something to practice my own homework on!