I wanted to do a shark as my next little drawing challenge.
I used an ellipse tool and a ruler with dark black ink for the basic shape, then added some watercolor for an intentional contrast in style and color. I played around with a few background layers; I think I like the medium-blue one best.
This sketch took about 10 minutes on my iPad as a little break after shopping at a Whole Foods, at which point I was happy with it, so I stopped.
It is a perfect shark drawing? No. Did I have fun doing it? yes.