Great work! I think some of your values could be made clearer if less white of the paper showed through. If you want cleaner tone without having to spend a lot of time on it, try using the flat plane of dull pencil to get broader strokes of value that overlap each other. Hope this helps!

These are beautiful!

Overall, I think you've done a great job separating your values clearly and you have a nice balance of big, medium, and small shapes. Your shading is also very nice and clean. I think you could make these thumbnails even better if you work a little smaller (to prevent adding too much detail) and think more about big swatches of value rather than focusing on the exact contour of the shapes. So you will be thinking more about the size, value, and placement of a shape rather than what the shape itself looks like. Your shapes are nicely designed and could be even better if you added some sharper corners to them in places, so that you have a balance of straights and curves. Great job! I am no expert on anatomy or figure drawing but I have heard Stan advise to do figure drawing before anatomy, as the anatomy course assumes you already know some concepts that are covered in the figure drawing course. Hope this helps!

I like to rotate the charcoal when I'm drawing to keep it sharp. You don't have to stop and sand it because the paper is sharpening it for you. Really nice job with this value scale! The graininess looks like the paper texture to me.