The Use of Feynman Diagrams in Physics Education: Opportunities, Challenges, Practices

This thesis explores the potential of Feynman diagrams as educational tools in upper secondary physics education, specifically for teaching particle physics concepts. It is set within the design-based research (DBR) framework, meaning learning materials incorporating Feynman diagrams were designed and evaluated while obtaining theoretical insights into learning processes. Feynman diagrams are a widely used tool in particle physics and have, therefore, found their way into physics textbooks and popular culture. Students interested in particle physics will come across them. However, the complexity of these diagrams also raises concerns about their suitability as educational content. On the theoretical side, this project addressed two key research goals: a) Identifying the opportunities and challenges of using Feynman diagrams in particle physics education. b) Developing specific design principles for designing and using learning materials that effectively leverage Feynman diagrams. On the practical side, the outcome was an online learning environment that interested students can use to learn about particle physics. As mentioned in the beginning, the project followed the DBR framework. Interviews with four experts on particle physics education were conducted to investigate the opportunities and challenges of Feynman diagrams in physics education. Learning goals that can be achieved with Feynman diagrams were derived from these interviews and literature. A draft of the learning material was designed based on the learning goals and design principles from multimedia research. The material consisted of graphics and English-speaking textual explanations to convey concepts of particle physics with Feynman diagrams, which students typically took between 20 to 30 minutes to work through. This draft was evaluated in two rounds with 72 international students between 16 and 20 years at CERN and, after redesigning and creating a German version, in a third study with 33 students between 15 and 19 years in two German schools. The evaluation studies used eye-tracking to investigate students' visual strategies and cognitive processes. Think-aloud protocols and questionnaires about prior knowledge in particle physics, cognitive load, motivational factors, and conceptual understanding supplemented the eye-tracking data. Four progressing educational opportunities could be derived from the expert interviews and relevant literature: Feynman diagrams offer a clear and intuitive way to represent \textbf{charge conservation}, a crucial concept in physics, especially particle physics. They can introduce the concept of interaction particles, a key concept of modern physics, contrasting it with the classical, non-local interaction view. They help illustrate the superposition principle and the role of approximations in particle physics, unveiling the quantum nature of particle physics and, thereby, a more accurate picture of the field than usually painted in popular depictions. By understanding how Feynman diagrams \textbf{connect theoretical and experimental particle physics}, students gain a deeper understanding of the nature of science. The first and second eye-tracking studies revealed that students use different, diagram-dependent visual strategies to examine Feynman diagrams based on the depth of their processing. The eye-tracking data of the third study demonstrated that various types of diagrams have different needs of cognitive processing, that students can learn through examples of Feynman diagrams that visualise charge conservation to focus their attention on relevant parts, and that a focused and systematic viewing behaviour is beneficial to solve tasks with Feynman diagrams. Furthermore, responses to open comprehension questions in the third student study revealed students' difficulties with subject-specific terms and concepts (like "weak charge" or "interaction particle") but no inherently stable or widespread inadequate conceptions. From these results, \textbf{challenges} that come with using the diagrams in education can be derived, which are classified into three categories: Students have difficulties with concepts like charge conservation and interaction particles, requiring careful instruction and practice. The complexity of Feynman diagrams, including non-sequential elements and arrows, is challenging for some students to decipher. Using technical terms in particle physics confuses most students. Furthermore, certain \textbf{specific design principles} can be derived from the project to address these challenges: Foster the development of different strategies (e.g., reading vertices forwards and backwards or identifying anti-particles) for examining Feynman diagrams to enhance their understanding. Present the Feynman diagrams in a well-defined progression, starting from simpler diagrams and gradually increasing complexity. Introduce foundational terms and definitions before using them in the explanations of diagrams to mitigate confusion. The results of this thesis demonstrate that Feynman diagrams can be valuable tools for teaching particle physics concepts in upper secondary education, provided the challenges are addressed with appropriate practices. However, further research should be done to explore the broader application of Feynman diagrams in science education.