First, the girls drawings.
I had trouble with the second profile, right when I hit the forehead to nose transition. I started to parallel the left side, inside of doing a mirror image. I had to stop, erase and then think "vase" in order to get going again.
The upside down drawings were fun. Unfortunately the girls didn't try them yet. Hoping they'll catch up. I may find a simplier drawing for them to try first, since they were both intimidated by the Picasso.
First, upside down. The right side up. This was an interesting exercise. I was mostly able to just draw, without thinking about what part I was drawing. Hands and face were tough to do this with, I knew I was drawing the hands. For some things I thought it helped me to remember what they were like the button holes. It also helped to look at adjacent lines to figure out how long or short another line was, to help keep the proportions right.
Now spiderman, just for extra practice. I didn't take as much time with this drawing and it shows, especially in the legs and feet.
See the other's drawings on Simcha's blog.