This study intends to investigate the evaluations of prospective teachers on STEM education, based on their experiences with planning and implementing STEM activities. The research's study group, designed qualitatively, is composed of 18 prospective teachers who graduated from the department of mathematics, 16 prospective teachers who graduated from the department of chemistry, 9 prospective teachers who graduated from the department of physics engineering and one prospective teacher from the department of textile engineering. STEM education programs carried out within the scope of the research lasted for 12 weeks, with four hours per week. Prior to the training programs, it was determined whether the prospective teachers had previous knowledge of STEM. After six weeks of training, study groups were formed which were composed of prospective teachers from different branches. Each study group performed what they thought was an STEM activity. A structured interview was undertaken with the teams following completion of the activities. The content analysis method was used to analyze the data gathered from the interviews. As a result of the research, it was determined that the applicability of the activity, compliance with the disciplines of STEM, being instructive and the features of the learning outcome are the selecting criteria in determining STEM activities applied. Prospective teachers mentioned a few problems they encountered during the activities. It was found that the participants thought to implement STEM activities in their professional lteacing routes, but some participants had reservations about the preparation stage and In this context, the most obvious drawbacks about the preparation phase of the activities are the material supplementation and the preliminary preparation of the activities. The drawbacks regarding the implementation process were caused by concerns such as time consuming activities, in efficient implementation of STEM activities, lack of cooperation between students, lack of active participation of students and a lack of materials.