To raise individuals who research, question, produce and most importantly think about a subject; it is very important for the future of the country. In order to gain these skills, countries make changes in education and adopt new educational approaches. One of these approaches is the STEM education approach. One of the applications of STEM education is the engineering design process. In this study, it was aimed to investigate the effect of the application process of engineering design-based STEM activities developed by pre-service primary school mathematics and science teachers on the decision-making skills of pre-service teachers. In the research, one-group pre-test - post-test weak experimental design, which is one of the quantitative research methods, was used. The study group of the research consists of a total of 36 preservice teachers studying in the last year of a state university in the Western Black Sea Region. "Decision Making Skill Test" was applied to preservice teachers as a pre-test and post-test. The implementation process was completed in a total of 14 weeks. In the first week of the implementation process, general information about the process was shared and the "Decision Making Skill Test" was applied as a pre-test. Between the second and fifth weeks, pre-service teachers were given theoretical information about STEM education and engineering design. In the sixth and seventh weeks, the researcher applied two sample activities based on engineering design to the preservice teachers. In the next six weeks, pre-service teachers developed and applied engineering design-based STEM activities. Engineering design-based activities were implemented using the engineering design process. The engineering design process steps used in the study; defining, researching, imagining, planning, creating, testing, developing and communicating. Paired sample t-test was used to compare the changes in the decision-making skills of the pre-service teachers with the pre-test and post-test. As a result of the research, it was seen that the engineering design-based STEM activity development and implementation process made a significant difference in the decision-making skills of pre-service teachers.
Engineering design process, STEM, decision making skill