This study investigated the effects of 3D model building activities with block codes on students' spatial thinking and computational thinking skills. The study group consists of 5th grade students in a secondary school in the Central Anatolia region of Turkey. For the study, a pretest-posttest control group was utilized within the experimental design. A total of 66 students participated, 23 in the experimental group and 43 in the control group. While the activities prepared on the Tinkercad platform were applied in the experimental group, the courses were taught using the traditional teaching method in the control group. The study covers a period of three-weeks in the course information technologies and software. The study used the computational thinking levels scale and spatial thinking test scales as data collection instruments. The data was analyzed using both descriptive statistics and independent samples t-tests. Based on the study findings, there were no significant differences observed in the levels of computational thinking skills levels and spatial thinking test scores between the experimental and control groups.