Girl with a big bag

My friend Joie is doing a sketch-a-day thing this month and since I have to be a copy cat, I'm going to attempt to do the same.

Check out her stuff @: http://www.joieart.net/

Anyhows, I saw a girl earlier with a book bag on her back, it wasn't an overly big bag by any mean but the way she was standing it looked like it was full of rocks. This is the quick sketch I did and how I imagined the bag from her posture.