This research was conducted to examine the conditions under which learner-generated illustrations serve as an instructional strategy promoting conceptual change. Specifically, the nature of students' misconceptions and the effects of student-generated descriptive drawings on conceptual understanding of scientific principles associated with the law of conservation of energy were studied. Students were randomly assigned to groups in which they copied an illustration, generated a drawing, or wrote a description about the principles. A statistically significant difference on a posttest conceptual understanding measure was found between students who generated descriptive drawings and those who wrote in a science log. Students who copied an illustration also scored higher than the writing group, but not at a significant level. Also, the quality and number of concept units present in the drawing/writing log were significantly correlated with posttest and delay test scores. Findings suggest that under certain conditions, descriptive drawing is a viable way for students to learn scientific concepts, a finding which supports the use of generative drawings as a conceptual change strategy.