Five experiments were conducted to investigate the relative effectiveness of 2 alternative instructional strategies. Students who were engaged in studying worked examples that emphasized understanding and remembering procedures and concepts were compared with students who were engaged in imagining worked examples that emphasized imagining procedures and concepts. It was hypothesized that students who held prerequisite schemas would find imagining to have a beneficial effect on learning, compared with studying the material, whereas students who were less knowledgeable would find imagining to have a negative effect on learning, compared with studying. Experimental results were in accord with our hypotheses. It was concluded that, under specific circumstances, encouraging students to imagine procedures and concepts can substantially facilitate learning.