In this study, it was aimed to reveal how the pre-service teachers who were educated in the primary school teaching program experienced the problem-based STEM application performed in Science and Technology Teaching (STT) I and which skills they employed in the process. The research was carried out with a case study, one of the qualitative research approaches. Easily accessible sampling metho was used to identify participants. In this context, 41 classroom teacher candidates who were studying in their third year in the classroom teaching program at the education faculty of a university and taking the STT I course participated. The research data were collected through semi-structured interviews and observations. Descriptive analysis technique was used to analyze the data in the study. The interviews and the data obtained from the recorded videos about the STEM activity that the primary school teacher candidates conducted within the scope of the STT I course, "The Studies of Primary School Teacher Candidates in the STEM Implementation Process", "The Skills and Affective Characteristics of Primary School Candidates Employed in the STEM Implementation Process", "Primary School Candidates' Opinions on the STEM Implementation Process ”under the themes in the form of findings. As a result of the research, it was seen that the teacher candidates both followed the engineering design steps and used interdisciplinary skills within the scope of an engineering design task presented in a real life context.