This paper addresses the accumulating knowledge of prospective teachers of secondary school mathematics and their acquired proficiency during the course "Psychological aspects of mathematics education," in which we discussed theoretical models including the intuitive rules theory. Participants' performances are examined by means of an extensive report of two episodes, one during the course and one afterwards. These episodes marked different stages in the prospective teachers' analysis of their own and of students' solutions, which led me to conclude that exposing prospective teachers to the intuitive rules theory is important, since their familiarity with the theory provided them with a tool to reflect on their own mathematical solutions (subject matter knowledge; SMK), on others' solutions, and on the tasks (pedagogical content knowledge; PCK).