This thesis aims to provide possible applications of triathlon in the modular course system of school sports. Additionally, potential benefits of peer learning in triathlon training groups are demonstrated and supported by practice-oriented lesson plans. The theoretical part of this thesis offers an introduction to the subject area Triathlon and includes its historical development, different competition formats and features of triathlon as a booming trend. Next, the phases of triathlon-specific training of young athletes are dealt with in relation to the physical and psychological development of children and young adults. In this context, the importance of a varied physical education and physical capacity is highlighted. After having discussed the key elements of triathlon training, relevant features for the implementation into the field of physical education in school are presented. This includes a description of methods and exercises as well as organisational considerations. Furthermore, central goals and the current curriculum of the ‘Neue Oberstufe are described and relevant skills and competences are discussed.In order to put these theoretical observations into practice, a teaching module for triathlon is designed and concrete contents as well as an organisational framework are planned. Finally, exemplary lesson plans are elaborated and specific exercises are explained in detail.