The one above her is an example of what my art instructor calls five-minute warm ups. When you finish the warm up then you can go back later and really work on the details.
This one is a spaceship! Just kidding it's a cup. This is an example of staring and staring at on object and then putting all the highlights and shadows on the paper.
So, why use charcoal?
Charcoal is very easy to blend. It is a fun and easy way to really practice highlights and shadows which are very important building blocks in realism drawings.