"Having essential questions drive curriculum and learning has become core to many educators' instructional practices. Grant Wiggins, in his work on Understanding By Design, describes an essential quetion as:
A meaning of “essential” involves important questions that recur throughout one’s life. Such questions are broad in scope and timeless by nature. They are perpetually arguable – What is justice? Is art a matter of taste or principles? How far should we tamper with our own biology and chemistry? Is science compatible with religion? Is an author’s view privileged in determining the meaning of a text? We may arrive at or be helped to grasp understandings for these questions, but we soon learn that answers to them are invariably provisional..."
Via Beth Dichter