There are anthologies of great literature and primary documents, but why not “30 for Under 20: Great Nonfiction Narratives?” Until such editions appear, teachers can find complex, literary works in collections like “The Best American Science and Nature Writing,” on many newspaper Web sites, which have begun providing online lesson plans using articles for younger readers, and on ProPublica.org. Last year, The Atlantic compiled examples of the year’s best journalism, and The Daily Beast has its feature “Longreads.” Longform.org not only has “best of” contemporary selections but also historical examples dating back decades.