This study investigates the learning of the concept of functions in an adidactic learning environment, explains the five phases of the adidactic learning environments defined in the Didactic Situation Theory and their interactions with the milieu generated within the given problem state of the students. It was carried out with 33 ninth grade students from an Anatolian high school in Balikesir. This qualitative study was designed as a case study. Descriptive analysis was used to analyze the data from students' worksheets, and the transcriptions of video records in order to investigate the outcomes of an adidactic learning environment in detail. Students' performances in the teaching process were evaluated with a checklist for problem-solving, construction of function knowledge and interaction with the milieu. The results showed that the basic conditions of an adidactic learning environment were provided, the students with a high interaction with the milieu constructed function knowledge by completing each stage. The students' display rates for the indicators on the checklist were 70.90% for problem-solving, 77.77% for construction of function knowledge, and 80.00% for interaction with the milieu.