The present study reports on the development and evaluation of a classroom module to train scientific thinking skills. The module was implemented in two of four parallel sections of introductory psychology. To assess learning, a passage-based question set from the medical college admissions test (MCAT[superscript 2015]) preview guide was included as extra credit on the final exam in all sections. This provided an outcome that was distinct in content from the module, while tapping the same underlying scientific thinking skills. Students in the experimental classrooms answered more questions correctly on targeted scientific thinking skills than students in the comparison classrooms. These data support the benefit of targeted activities for training scientific thinking skills in introductory psychology.