First Paragraph Should contain a brief explanation of your rule. | Because the fingernail bits will grow into fingers. |
Second Paragraph Explains what happens. | The process of how finger nails grow into fingers is explained. |
Third Paragraph Explains the consequences of what happens. | The author described the problems that these wayward fingers caused around the home. |
Forth Paragraph Restate the rule and explain why to follow. | The author tells you not to bite your nails, but if you do, send the bits to an accordion factory where they can be put to work. |
This would be a level three example. To go for a level four, you would need to extend the details like the author does when he talks about how these individual fingers form gangs and then describes what the gangs do.