The lesson on Nested Classes is another which could be skipped in its entirety by the beginner, without loss of continuity. And while the tutorial argues enthusiastically that: "There are several compelling reasons for using nested classes", I can't see myself using them for some time, if ever.
I read the sample page with an open mind, prepared to be persuaded otherwise, but the example was so trivial, it did the opposite. I remain convinced that the home programmer can live without nested classes. And the Summary page wasn't really a summary, and could have been appended to the opening page, thereby reducing bloat in the table of contents.
And if you ignore the questions and exercises, this concludes the trail on classes and objects.