Student understanding of the real images produced by converging lenses and concave mirrors was investigated both before and after instruction in geometrical optics. The primary data were gathered through interviews in which undergraduates taking introductory physics were asked to perform a set of prescribed tasks based on a simple demonstration. The criterion used to assess understanding was the ability to apply appropriate concepts and principles, including ray diagrams, to predict and explain image formation by an actual lens or mirror. Performance on the tasks, especially by students who had not had college instruction in geometrical optics, suggested the presence of certain naive conceptions. Students who had just completed the study of geometrical optics in their physics courses were frequently unable to relate the concepts, principles, and ray-tracing techniques that had been taught in class to an actual physical system consisting of an object, a lens or a mirror, and a screen. Many students did not seem to understand the function of the lens, mirror, or screen, nor the uniqueness of the relationship among the components of the optical system. Difficulties in drawing and interpreting ray diagrams indicated inadequate understanding of the concept of a light ray and its graphical representation.

Although several successful inquiry-based physics and physical science curricula have been developed, little has been published that describes the development of these curricula in terms of their basic design principles. We describe the research-based design principles used in the development of one such curriculum and how these principles are reflected in its pedagogical structure. A case study drawn from an early pilot implementation illustrates how the design principles play out in a practical classroom setting. Extensive evaluation has shown that this curriculum enhances students' conceptual understanding and improves students' attitudes about science.

This paper reports on a study that was designed to investigate the knowledge about image formation exhibited by students following instruction in geometrical optics in an activity‐based college physics course for prospective elementary teachers. Students were interviewed individually, using several tasks involving simple apparatus (plane and curved mirrors, lenses, and prisms). The diagrams drawn by the students and the verbal comments they made provide evidence that their knowledge can be described as an intermediate state, a hybridization of preinstruction knowledge (which is dominated by a holistic conceptualization) and formal physics knowledge. We infer from our data the core concepts and main ideas of the postinstruction students' hybrid knowledge. Finally, by comparing preinstruction and formal physics conceptualizations of image formation we argue that a strong type of knowledge restructuring (in the sense of Carey, S., 1986: American Psychologist, 41, 1123‐1130; Vosianou, S., & Brewer, W.F., 1987: Review of Educational Research, 57, 51‐67) is required for students to acquire the latter.

No abstract