Students' understanding of light and its properties: Teaching to engender conceptual change

Over the past 15 years there has been strong international interest in students' ideas concerning phenomena taught in science. Many of these ideas, which students may have prior to instruction or have developed during instruction, have been well documented in physics content areas such as heat, motion, the particulate nature of matter, and light. If the students' ideas conflict with generally scientifically accepted ideas they are labeled variously as students' conceptions, misconceptions. preconceptions, childrens' science, alternative conceptions, or alternative frameworks depending upon the researcher's view of the nature of knowledge (Gilbert and Watts, 1983). Students' conceptions which are different from the scientifically acceptable ideas are often strongly held, resistant to change, and can hinder further learning (White and Gunstone, 1989). Students may undergo instruction in an area in science, perform reasonably well in a test on that subject, yet not undergo any meaningful change in their conceptions regarding the phenomena being investigated. Indeed, even if a measurable change did occur, in time the learned school science may be forgotten and supplanted by these earlier, firmly held beliefs. The topic of light presented the authors with similar concerns that instruction in the regular high school curriculum resulted in many students constructing knowledge which was not congruent with acceptable scientific understanding.