Educators have long emphasized the importance of relating mathematics to everyday life situations. During the primary school years, mathematical modeling activities play an important role in this regard. Through a mathematical modeling activity prepared in accordance with the length and area measurement learning outcomes in the primary school 4th-grade mathematics curriculum, the purpose of this study was to determine students' mathematical modeling competencies. The study adopted a qualitative approach using a teaching experiment model. The study involved three students selected from 33 in a state primary school through criterion sampling. "Farmer Uncle Hüseyin" model eliciting activity (MEA) was given to the focus group to work on, and the whole process was videotaped. Each video recording was transcribed in detail. Transcriptions, student handouts, and researcher field notes were analyzed using the mathematical modeling competencies cycle developed by Blum and Kaiser and adapted by Maaß (2006). Modeling competencies of students were found to be at different levels. Based on the study, the students' warm-up activities, the context of the MEA, and their previous modeling experiences all contributed to the students' representation of different levels of modeling competency. Due to the frequent use of multiple-choice questions in their classrooms, students also had difficulty interpreting qualitative data and understanding the mathematical task they were given.