I don't necessarily believe the "subtypes" would necessarily need a chapter to themselves. I see it more as 

Chapter One: What is Roleplaying? 
- Definition 
1.1 - Different types like LARPing
1.2 - Different types like Text Based
Etc, etc

It coul just branch off chapter one instead of giving EACH little thing a chapter of its own. And the Units I pictured more like: 
Unit One: Fundamentals of Roleplaying (what it is)
Unit Two: Maybe something like Character Sheets and such 
And so forth and so forth.