This study aimed to determine preschool teacher candidates' ability to design Science, Technology, Engineering and Mathematics (STEM)-focused activities and their attitudes towards STEM. The research method of the study was determined as a case study. The study was carried out with 35 preschool teacher candidates in the 3rd grade of the Preschool Education program. In the study, it was seen that the preschool teacher candidates had prepared the STEM activities at the end of the 14-week STEM education given to them, and they were able to design a sufficient level of activity. In addition, it is seen that the 14-week training provided has a positive effect on their attitudes towards STEM. However, this period is not sufficient to develop attitudes. Therefore, it can be suggested to examine attitudes towards STEM in longer periods.