Dealing with "information smog"
A case study is a focus on actual or real situations in order to derive meaning, examples and lessons from the players and events that comprise the actions and outcome. For example, the Grand Canyon Dams, or Galileo's Trial, or the Everglades, Pacific Northwest conservation, or New York City's water.
The use of case studies can pinpoint for learners where the trivial details diverge from the core, or essential problems that drive the conditions of the situation to the outcome for us to assess. In assessing or understanding the "lessons" of a case, we are forced to see how critical details converge to produce an outcome. Distinguishing between core and peripheral facts, or between essential and trivial matters allows readers to think critically about how things turn out when people and institutions act to assure their interests.