The plot of a story involves the following elements: exposition (where we are introduced to characters and setting), inciting incident or conflict (which is the problem that begins suspense), rising action (when suspense builds), climax (the highest point of tension), falling action (when the suspense lessens), and resolution (when the problem is solved and/or things return to normal). This novel has a plot that's fairly easy to follow.
The exposition is when we are exposed, as readers, to the characters of Greg and Maura (and the idea of Chunky Comics) in the setting of middle school. The inciting incident happens when Maura creates a set of comics that compete with Greg's and when the school principal resists the idea. The rising action is all about Greg's and Maura's competition and the principal's antagonism. The climax is the Committee Meeting where the fate of Chunky Comics is decided. The falling action explains the reasoning behind the "half for learning and half for profit" idea. The resolution involves Greg's and Maura's resulting friendship and continuation of middle school.
In conclusion, this young adult novel is a perfect book to teach middle schoolers about plot in that the plot elements are clearly defined and easy to spot as well as easy to explain.