In spite of being readily available, photographs have played a minor and passive role in science classes. In our study, we present an active way of using photographs in classroom discussions with the use of a classroom response system (CRS) in middle school astronomy classes to teach the concepts of day-night and seasonal change. In this new pedagogical method, students observe objects or phenomena in photographs and use the information to develop understanding of the scientific concepts. They share their ideas in classroom discussion with the assistance of the CRS. Pre- and posttest results showed that the new pedagogy helped students overcome primitive conceptions and enhanced their understanding of the concepts. The observation of the rich details of photographs played three pedagogical roles in classroom discussion: easing students' anxiety about learning a new scientific concept; continuous stimulus of learning; and as evidence or data.