Here is the process of creating a scene for animation demonstrating Yogi Bear (c Hanna Barbera) pitching a baseball. You first will see storyboards depicting the action. From that an animator will create ruff thumbnails to describe the key poses of the action. From these the animator will redraw his animation full size and time the action accordingly for the best visual effect.
Storyboards depicting the action to be animated
Ruff thumbnails used to depict the key poses of the action to be animated...frame numbers added after the timing has been worked out.