This work aimed to describe and analyze the potential of a contextualized didactic activity for the teaching of Mathematics with students of the first year of High School. For that, we used the action research methodology to investigate an activity on the use of cell phones in the classroom in the teaching of Mathematics. In the analysis of the results, two categories emerged: students' understandings in Mathematics from everyday questions, and research as a potential for teaching and learning in Mathematics. From the discussion held in these categories, we argue that by carrying out a contextualized and investigative practice in the teaching of mathematical concepts, we enhance the process of forming conscious and critical subjects.