This study aimed to reveal mathematical modeling processes and difficulties encountered in model-eliciting activities (MEAs) of 8thgrade students in a STEM education setting. This qualitative research is a case study conducted at a public school located in the central districts of a large province in the Mediterranean Region. The participants of the study are groups of 8th-grade middle school students in a classroom (five groups of students), which were selected with the purposeful sampling method in the 2019-2020 academic year. The student groups were applied an MEA according to a certain plan, and the students' modeleliciting processes were recorded. Then, the participants' modeling activity process and the cognitive activities they put forward through documents and interviews were examined by considering the stages in a mathematical modeling process. For this purpose, each group's modeling process was analyzed qualitatively using the modeling cycle of Blum and Borromeo Ferri (2009). The results of the study revealed that these 8thgrade students faced some difficulties in the process of modeling. These difficulties were identified in 7 categories: understanding the problem, establishing a model, using mathematics, and explaining the results, - which are the four stages of the modeling process- working within a group, verifying the created model, and time management.