Problem-Centered Constructivism era
Barrows and Tamblyn popularized problem-based learning in medical education during the 1980s, organizing curricula around authentic ill-structured problems that drive collaborative inquiry and facilitator-guided exploration. David H. Jonassen articulated constructivist design principles for learning environments that leverage ill-structured problems, cognitive apprenticeships, and student-driven meaning making. John Sweller's cognitive load theory underpinned the use of worked examples to reduce extraneous cognitive load and scaffold novice problem solving. The Cognition and Technology Group at Vanderbilt, especially John Bransford, Ann Brown, and Rodney Cocking, advanced anchored instruction and situated learning to tie knowledge to context-rich, cross-disciplinary tasks.