Enrichment is far more effective than edutainment.  As students reach high school, they search for more "meaning" in lessons than "fun" alone.  Enrichment is the key to both engaging students and establishing that meaning.  For effective teachers, striving to make every class "fun" is a secondary concern to building lesson plans that allow students to explore and connect with the lesson themselves.  Plus, making every class fun is a daunting task, especially for the teenaged brain.