Practices that take into account youth and adult education (YAE) are still rare in the literature.The present work applied an investigative activity with YAE students from the last year of middle education, in the discipline of sciences, about the methods of construction of science and tests of variables. From the categorization of metacognitive incidents used, it was verified that the stimulus to the argumentation that the investigative activity potentiated was fundamental for the students to conclude the activity successfully. [For the full proceedings, see ED619611.]