We drew/painted an elephant and then either a cat or a dog while learning how to use the brush tool and eraser. The challenge was to use only a single layer.
Elephant (done using a mouse):
Since we were only using one layer and a mouse, I made use of various selections and low opacity soft brushes to paint the elephant. To get the silhouette I initially made large brush strokes and then erased away to get the right shape/s, the second time making the elephant I used the polygonal lasso tool.
Cat (done using a Wacom tablet):
For the cat drawing I used a Wacom tablet and a combination of the brush tool and the eraser.
Update: We have also learnt how to crop, edit destructively and edit non-destructively using the healing brush tool.