[xnwczcxq] View three pages at a time

On the left, an illustration of the "Before" state.  In the center, a description or instructions on the change to the state.  On the right, an illustration of the "After" state.  This "After" illustration gets repeated on the next step as the "Before" state.

Fairly easy on a wide computer screen.  Create a physical book whose pages can turn this way.  (Hopefully more convenient than a scroll.)