Conceptions of shadows by finite light sources

Light has great importance for life on Earth. In physics it is described as electromagnetic waves. Light is emitted by light sources. When light falls on an opaque object it forms a shadow. The current scientific knowledge about the children's conceptions of light and visions are based on two studies carried out by the Science Department of the University of San Diego, in the United States. The studies were held in the local Science Museum and included students aged eight to fourteen years. In the first study different light sources, barriers and screens were placed in different positions, as an interactive exhibit. Students have investigated how the light spreads through a small hole and what images generate on the screen. The staff involved students in conversations and suggested moving the props. In the second study the layout of the screen contained opaque objects and a light source in the form of a cross. The students studied the shadows on the screen when the opaque object is close to the screen, half way between screen and light source and close to light source. Playing with shadows is always interesting and still relevant, irrespective of age. This master’s degree thesis illustrates how the students in our primary school link the following concepts: light source, obstacle and screen and distances between them. What image is produced on the screen? Is there a shadow in the dark? These and other questions were answered by 4th and 9th grade students, so that age of the students is comparable to previous studies. By conducting experiments, I encouraged students to think about this topic. Similar to previous studies, I have prepared a layout council slot or object and the screen. In the experimental groups students first carried out the experiment, then they solved the questionnaires. In the control group, I performed the experiment after they solved questionnaires. I wanted to show that for the correct perceptions and better understanding of physics, it is necessary to experiment as much as possible. Three students took part in a semi-structured interview, so that I could find out their thinking. Interestingly, the results of our students were different from the results of previous studies