I found this workshop quite difficult as I had never done straight-ahead animation before and the materials I chose to use didn't really lend themselves well to the "erasing" aspect of straight-ahead.
The first animation I did was of a person walking in the raining, briefly obscured by a double-decker bus. I quickly found that charcoal I was using couldn't be erased very well on the handmade paper I was using.
I therefore made another animation exclusively using watercolour. This work a bit better!