The purpose of this study is to determine the student experiences for a lesson plan designed according to Didactic Situation Theory using Cabri-Geometry software. In line with this aim, we worked with four seventh grade students in Bursa. Within the scope of the study, students were given a black box activity involving the symmetry transformation made in the computer environment. Descriptive analysis of qualitative research methods was performed, and data were processed according to the thematic framework. The students were invited to do our black box activity. As a result they made some group discussions about their process of learning and discovering concepts and gave feedback on their experiences. All five phases of the Didactic Situations Theory have been exemplified in the findings of the study. The results showed that students could construct the concept of symmetry with its properties by means of the constructive environment prepared with the black-box activity.