Students’ conceptual change in geometrical optics

Educational research provides information on specific ways in which conceptual changes occur when students learn geometrical optics. Students' ideas may be represented as clusters of 'facets‐of‐knowledge', each cluster specific to an optical setting. When students' ideas undergo conceptual change these facets of knowledge are transformed. The resulting 'hybrid knowledge' incorporates ideas from classroom instruction as well as some beliefs students held prior to instruction. It appears that relevant pre‐instructional knowledge could be described within 'holistic conceptualization', while hybrid post‐instructional knowledge may be described in the framework of 'image projection conceptualization' (IPC) contrasting with the scientific view elaborated in 'point to point flux mapping', conceptualization. The transition from holistic conceptualization to IPC, neither of which is correct, is related to students' incorrect interpretation of the light‐ray concept. Specific activities are suggested to encourage an accurate approach. Intriguingly, the conceptual change which students undergo appears to be similar to the historical development of optics.