Moved the chin over the mouth when finishing because it looked like I sculpted the mouth way down. Any mistakes besides that?

Finally my attempt to do the skull. Did it from a small plastic skull I had purchased. Do think I could raise the forehead just a bit.

I thought I would try carving a skull rather using clay for this assignment. I found it quite a bit more difficult to sculpt using ONLY a subtractive process, rather than being able to add and subtract, correcting my mistakes. I laminated pieces of plywood and used their vertical orientation to help me maintain the bilateral symmetry of the skull. My piece is not as abstract as you suggested in the assignment, but I really enjoyed this exercise.

I'm neither beginner nor expert. I'm here to get better along with lessons. When I finished sculpting my models something seems off. Hardest part is, I don't even know what's wrong. Help me to find the odds (including this model and upcoming ones) and make me grow like you. I will try to keep up with the upcoming lessons. Thank you Andrew.