Objective:

understand the relationship between teacher action and reflection in the construction of the Pedagogical Content Knowledge (PCK).

Methods:

qualitative research from symbolic interactionism; simple case study, based on: semi-structured biographical-professional interview, observation and recording of a class and think aloud interview.

Results:

the inductive analysis of the data generated the categories: action and teaching reasoning.

Conclusions:

the teacher relates PCK to the mechanisms through which he can interact with students and make the class sufficiently playful and meaningful for them to internalize it; central to PCK is the context in which it is taught -university, students, educational system-; PCK is a particular construction of each teacher to improve and strengthen his pedagogical practice.