Women are underrepresented in robotics, and this may be partly due to the educational emphasis on mechanical applications rather than social applications of robotics. This study aimed to investigate whether teaching robotics using social robots increased girls' engagement compared to using more mechanical vex robots. 20 girls were recruited from school robotics classes. They were taught 30 minutes of VEX robotics and 30 minutes of social robotics in a counter-balanced order. Engagement was measured using questionnaires and observations. Results showed that girls were significantly more engaged in the social robot classes than the vex robot classes. This pilot study suggests a possible way to encourage more girls to study robotics.