Despite the benefits of teaching computational thinking (CT) and applying coding tools in schools, many teachers feel unprepared to use these technologies. Hence, we introduced CT concepts and coding tools to pre-service teachers (n=36; 17 in online class and 19 in in-person class), equipping them with digital competencies through activities with the topic of teaching geometry and measurement concept. We found a notable increase in their confidence in teaching geometry and measurement, implying that hands-on experience with coding tools may support pre-service teachers' mathematical content knowledge development. However, although improvements were observed, pre-service teachers continued to feel less confident with coding tools compared to the general technology applications in lesson planning, indicating that continuous professional development is needed for teaching coding. When comparing pre- and post-survey results within each group, we found that while the online class showed minimal changes in the post-survey results, those in in-person class experienced more substantial gains.