When Friedrich Kohlrausch developed the first "practical exercises" in 1860 to introduce his students to scientific experimentation, he had the following philosophy: "The widest possible scope (...) should preserve the necessary degree of intellectual self-activity (...) for the worker. It is not the task carried out according to a scheme that is of value, but the intellectual property that the worker acquires in carrying it out (Kohlrausch 1900).

Around 80 years later, Wilhelm Westphal adapted the practical course to the incipient mass operation at universities and designed experimental set-ups with precise instructions and sample solutions. The development of experimental skills and "scientific thinking", for Kohlrausch "the main purpose of the practical course", receded into the background. When carrying out the experiments, students no longer experimented independently but worked off a "recipe". Empirical studies show that students spend most of their practical time recording measured values. The execution of the experiments is hardly ever theory- or question-led or reflected upon (Haller 1999). A structured discussion or reflection on the method used, the measurement data collected or the calculated results does not usually take place in the lab course groups, although these aspects occupy a central position in scientific research.

The aim of the Paderborn Physics lab course is to promote the experimental skills that an experimental physicist needs for their research from the first semester onwards in a structured and consecutive manner with tasks that are nevertheless free. The experimental skills include developing the question, planning and dimensioning the experiment, setting up the experiment, testing and optimising, recording the measured values, evaluating the measurement, interpreting the results and reflecting on the experiment as well as the obligatory problem recognition and problem-solving skills. At the same time, the students' communication (e.g. judgement and discussion), social (e.g. ability to cooperate and listen attentively) and personal skills (time management, independence, ability to concentrate) should be systematically developed. Students should develop a "feeling for physics" over the course of the four semesters. This "feeling", combined with enthusiasm for their subject area, forms the basis for a successful career as a physicist in university or industry.

The Paderborn Physics lab course 3P extends over four semesters. Experimental skills are acquired systematically in stages based on the basic content areas of physics. While the content and cognitive requirements are gradually increased, the learning support realised by the supervisors and the materials decreases steadily. The aim is for students to have learnt the skills that are relevant to the physics research process by the end of the beginner lab course.

For the systematic training of experimental skills, the training of one skill, such as the assessment of experimental designs, linked to the subject area of mechanics, is closely instructed on each experiment day in the first semester. In the second semester, several skills are developed in longer phases and with less guidance from the supervisor on each experiment day. The complexity of the content in the field of electrodynamics and the associated scope of the experiment days is systematically increased over the course of the semester. At the same time, the supervisor increasingly takes a back seat so that the students gradually work more independently.

In the third semester, students work on the automation of experimental setups. At the end of the semester, they independently carry out their own project with a given question. The supervisor can be asked for assistance if required. The project is presented by the respective groups in the form of a scientific poster during the planning stage and in the form of a scientific presentation and report after completion of the project.

At the end of the third semester, students should be able to carry out their own project independently in all phases of the scientific research process. In the fourth semester, students work on their own project, from searching for a relevant question to presenting the results, using the open experimentation approach.

Five 90-minute lectures at the beginning of the first semester serve to impart the basic knowledge for structured experimentation, the recording of measured values, their evaluation and discussion as well as the writing of an initial publication in the form of a report. Following each lecture, the content is applied and deepened in classroom exercises with a specific task. Following the fifth lecture, students write their first lab report from the modules developed in the classroom exercises.

The lab course days are divided into alternating discussion and experimentation phases. Three teams of two develop, optimise or use different experiments on a common overarching topic (relating to content and skills facet). All six students discuss selected aspects of the experiments together in moderated discussion rounds.

In the typically three discussion rounds of a lab course day, students learn to exchange ideas in a well-founded and precise manner. The experimental phases are prepared and followed up, and theory and practice are linked both intellectually and linguistically against the background of the specific task. The students learn from each other and through the example of the supervisor the technical language of physics and category-led discussions, e.g. about the comparison of different measurement methods or the cause of measurement uncertainties.

On each lab course day, students work with different experimental set-ups and approach the main topic in different ways. They combine their technical and procedural knowledge with their experimental skills and thus develop their experimental expertise. They work together as a team, have to coordinate their approach and activities and work on their personal and social skills.

Students receive a wide range of material support during the lab course. Instructions have been developed for the preparation of the experiment days. These are structured in such a way that a detailed task for the experimentation day follows a subject-specific introduction to the topic of the day with reference to current research. The tasks, consisting of the subject content focus, the subject methodological focus and the cognitive requirement level, are communicated to the students in a transparent and differentiated manner in order to ensure in-depth preparation and thus a more effective learning process. In addition, students are given literature references.

From the second semester onwards, students are required to prepare for the experiment days in greater depth so that they can cope with the increasing complexity of the content. In addition to the literature references that continue to be used, students are given tasks to complete using the simulation programme LTSpice. The tasks become progressively more complex both within the individual experiments and over the course of the semester.

From the third semester onwards, students only receive the tasks for the experiment day and an introduction to the experiment topic in terms of methodology. Further preparation is carried out independently by the students.

In the fourth semester, students are allowed to independently develop a physical problem and are therefore fully responsible for developing the theoretical foundations.

The lab course supervisors play a central role in this concept: they are experts, role models and ambassadors for their subject area who play a key role in shaping students' enthusiasm for physics. They have the task of accompanying, promoting and guiding the students' self-directed learning process. Both in the discussion rounds and in the experimental phases, the supervisors provide impulses tailored to the students' individual competence levels or formulate questions to moderate the process instead of prescribing solutions or pointing out errors directly. In addition, the supervisors observe and evaluate the students' performance and give them constructive feedback.

The broad range of tasks of the supervisors in this concept requires comprehensive training. As part of a four-day workshop, led by an interdisciplinary team of lecturers, the participants develop the basic tools for the moderation of the lab course days and the learning support in the experimental phases, apply them in practical exercises and reflect on their own actions. Participants contribute their prior knowledge and professionalism to the structured learning process, develop existing skills and develop new ones.
The interdisciplinary team of specialised physicists and educationalists ensures the target- and application-oriented linking of physics and teaching/learning theory. The workshop is offered in cooperation with the Higher Education Develop Office at Paderborn University and is credited in the higher education training programme "Professional Teaching Skills for Higher Education" in NRW.