The aim of this study is to reveal the students' and pre-service teachers' understanding of light, sight and related concepts at different educational levels, from primary to higher education. A cross-sectional approach was used since the participants were of different age and educational level. The sample of this study consisted of 30 eighth grade primary school students, 26 eleventh grade secondary school students, and 42 student teachers. The data were collected through open-ended, multiple choice questions, and a drawing exercise. Findings showed that the participants' perspective and understanding of light and related concepts generally reflect what their syllabus covered at different educational levels. The participants look at light from two points of views; the effects or function of light and the nature or structure of light as a physical entity. As the participants-education level is advanced, they described light through its effects and interactions as well as its physical nature. A significant number of the participants were found not to be able to explain light related phenomena in scientific language, despite their knowledge about them. Some common misconceptions about light, light sources and sight process have been determined at all levels. This study also revealed some implications for the syllabuses and teaching of the topic. (Contains 7 tables and 2 figures.)