Problem-based learning is both an instructional method and an educational theory, based on creating active, hands-on classroom experiences that promote engaged learning. Developmental psychology, educational theory, and even the philosophical domains of ontology and epistemology are always in flux, with each new theory or emerging philosophy altering the conversation. Even though most educational theory focuses on children, this does not prohibit its applicability to our purposes in higher education. Traditional approaches to education might be termed instructivism, rooted in John Locke's Essay Concerning Human Understanding in which Locke proposes that the human mind is a blank slate at birth, filled by accumulated experience. A philosophy of andragogy leads instructors to treat their students more like peers than children who need instruction in behavioral standards. It also means understanding that older adult students may have encumbrances and responsibilities uncommon among typical 18- to 22-year-olds.