How prior knowledge affects students’ representational competences in ray optics

There is a broad consensus among science education researchers and cognitive scientists that students need to develop and understand multiple representations to deal with scientific concepts. The special difficulty in physics stems from the fact that students’ former schemata are composed of physical concepts based on everyday experiences. Students’ beliefs about how the world works are often in contrast to scientific explanations of physical phenomena.
Following recent research on conceptual change and cognitive science in physics educationinstructions have been developed that take into consideration widespread preconceptions that are reflected in external representations in order to support students in creating “scientifically appropriate” representations. In a first study (n = 57), we investigated whether these tasks help students to improve knowledge, problem-solving and conceptual understanding in ray optics with regard to picture formation. The study was designed as pre-and post-test quasi-experimental design. Students of two classes of the 8th grade in one
grammar-school formed real pictures by using a spherical concave mirror. Results indicate that a relatively short intervention targeted on representations in ray optics and taking into account widespread preconceptions can lead to a significant and practically important improvement of conceptual understanding. A second study (n ≈ 420), especially, focuses on investigating which kind of tasks support students’ in building up a mental model of picture formation and in creating appropriate representations as well as operating on them. Since
this study is still in progress, the research design and analysis methods are outlined.