Confucius and Aristotle were early proponents of learning by doing. Socrates modeled how to learn through questioning, inquiry, and critical thinking -- all strategies that remain very relevant in today's PBL classrooms. Fast-forward to John Dewey, 20th-century American educational theorist and philosopher, and we hear a ringing endorsement for learning that's grounded in experience and driven by student interest. Dewey challenged the traditional view of the student as a passive recipient of knowledge (and the teacher as the transmitter of a static body of facts). He argued instead for active experiences that prepare students for ongoing learning about a dynamic world. As Dewey pointed out, "Education is not preparation for life; education is life itself.