Experience becomes the foundation of teaching. Knowledge grows. The teacher is not there to convey the material. Rather, their role is to mediate between students and knowledge, as stated in Martin Kramer's didactic credo. His experiential educational concept of teaching as an adventure enables students to recognize and understand mathematical structures in a hands-on and group-dynamic way. Joy in play, cooperation, and personal development are the cornerstones of his constructivist didactics. Volume I offers practical suggestions on topics including geometry and measurement. "Mathematics as Adventure" is aimed at educators, trainees, and students in teacher training who are looking for ideas to design learning environments and wish to organize their teaching with greater appreciation and responsibility on the part of the students.