The present study aimed to determine the effect of Scratch-assisted expressions and applications on the Computational Thinking skills of pre-service teachers. For this purpose, the research was designed with an exploratory sequential design, a mixed research method. Thirty-three pre-service teachers participated in the study. Data were collected with Computational Thinking Scale before and after the applications conducted in the Instructional Technologies course, and with a survey form developed by the author and face-to-face interviews conducted with the participants at the end of the course. Based on the data obtained, it was determined that the applications conducted in the course improved the Computational Thinking skills of the participants. Although the improvement did not differ based on gender, it was determined that the differences were significant based on creativity, algorithmic thinking, and critical thinking sub-dimensions. Furthermore, it was observed that there was a positive and significant correlation between Computational Thinking and academic achievement. Also, pre-service teachers stated that Scratch applications contributed to the acquisition of Computational Thinking skills. It was suggested that the present study findings would contribute to future studies on Computational Thinking acquisition in similar courses.