When is an illustration worth ten thousand words?

In three experiments, students read expository passages concerning how scientific devices work, which contained either no illustrations (control), static illustrations of the device with labels for each part (parts), static illustrations of the device with labels for each major action (steps), or dynamic illustrations showing the off and on states of the device along with labels for each part and each major action (parts-and-steps). Results indicated that the parts-and-steps (but not the other) illustrations consistently improved performance on recall of conceptual (but not nonconceptual) information and creative problem solving (but not verbatim retention), and these results were obtained mainly for the low prior-knowledge (rather than the high prior-knowledge) students. The cognitive conditions for effective illustrations in scientific text include appropriate text, tests, illustrations, and learners. The two major media for communicating scientific infor-mation to students are words and pictures. In spite of the traditional bias toward verbal over visual forms of instruction, a growing research base suggests that text illustrations can have important effects on student learning (Levie Lentz,