Retention of a Double Slit Single Photon Interference Demonstration of Particle- Wave Duality

In the past there has been great faith in the power of laboratory activities and teacher demonstrations to enhance the learning of physics concepts. However, reviews of the effectiveness turned out to be disappointing [1-3] and have shown that lab activities and demonstrations need to be carefully designed and embedded in lessons to realize cognitive benefits [4]. Nevertheless, for secondary school quantum physics we developed a portable double slit demonstration mounted in a suitcase in which photons pass the slits approximately one by one and yet together produce an interference pattern. Based on experiences in 5 schools, we carefully designed the educational aspects of the demonstration and investigated its long-term learning effects through a written test of 68 students after 4 weeks and retention interviews after 4 months (10 interviews) and after 9 months (5 interviews). Students did remember the set-up and results of the demonstration quite well. They were quite aware of the unexpected and strange wave-particle behavior of quantum particles in the demonstration including the effect of measurement or observation on the outcomes. However, half of them still had trouble defining duality in their own words and most of them did not remember de Broglie particle waves and how that related to the double slit experiment.