The project KoM@ING aims to investigate the mathematical skills which are required in technical subjects of engineering bachelor courses. Our subproject is especially interested in the first-year-course " foundations of electrical engineering ". In order to do research on this subject we developed the concept of a " student-expert-solution " (SES) which was generated by analysing expert interviews. The SES is supplemented by the required resources and a didactical reconstruction, for example, typical mistakes, alternative solution approaches and learning goals. The SES of a basic engineering exercise will be presented. We find some discrepancies with the standard modelling cycle, as well as some surprising problem solving strategies.