The nature of key ideas in teaching high school physics: Three topics in optics, color, the speed of light, and light interference

The distinction between key ideas in teaching school science and key ideas in the disciplines of science is crucial and yet largely ignored in scholarly discourse about what science teachers should teach and what they should know. This dissertation seeks to clarify this distinction through investigating how and why the key ideas in teaching three topics in optics, color, the speed of light, and light interference, for high school students differ from the key ideas in teaching for prospective physicists or scientists.;The study found that the key ideas in teaching the three topics for high school students differ markedly in theory types, source analogues, and representations from the key ideas in teaching for prospective physicists or scientists; and that the differences are determined by differing purposes of teaching, knowledge backgrounds and experience of learners, and ways of selecting and formulating key ideas in textbooks.;This dissertation argued that not every idea in the discipline of physics can be taught to anybody of any age in a way that is intellectually honest to the discipline; that knowing the structures of the discipline of physics does not guarantee that physics teachers have the specific kind of subject-matter knowledge needed for teaching school physics; and that key ideas in teaching school physics constitute an essential component of pedagogical content knowledge.;This study calls for more empirical research on the nature of key ideas in teaching school science; development of a special subject-matter sequence for the education of science teachers; and development of a theoretical base for the construction of a science curriculum that bears a transparent relationship to the structures and development of science.;This study employed Dewey's idea about psychologizing subject matter and Harre's theory of referential realism as theoretical underpinnings. It consists of (1) a case study of two experienced physics teachers; (2) a comparative analysis of the key ideas in teaching the three topics at the high school level and the key ideas in the discipline of physics; and (3) interviews with the two physics teachers and with two optics professors.