Cartels: This section discusses cartels: collections of firms that organize in an attempt to increase their joint market power and raise profits.  A careful discussion of Figure 11.1 gives an opportunity to discuss how cartels raise profits by jointly behaving as a monopoly would behave.  It is worth keeping in mind that the next chapter on Game Theory will provide additional modeling tools for discussing collusion, so providing students with a solid intuitive explanation for why some cartels succeed and endure over time and others collapse is very useful.