This research proposes theoretical-methodological strategies and tools to guide teaching, reflection, and assessment on the practice of the prospective teacher of mathematics when performing teaching and learning processes on the notion of function. It exemplifies our proposal’s use, through the reflection and characterization of the didactic-mathematical knowledge, of a prospective Chilean teacher, underlying his practice of teaching the power function. For the development of our proposal, we used the theoretical-methodological notions of the Didactic-Mathematical Knowledge (DMK) model and micro-teaching contexts, understood as rich and essential spaces for teacher education. As a conclusion, we could observe that the theoretical-methodological proposal here presented serves to systematize the reflection and assessment processes of teaching practice (one’s own or that of others) for the teaching of functions, and, thus, determine (or anticipate) actions that improve the teaching processes on this important mathematical notion.