Shortages of STEM teachers have presented challenges to school employers for decades. Additionally, universities are tasked to produce science teachers of better quality, equipped in both content and pedagogical strategies. Undergraduate STEM majors with no prior inclination toward teaching were strategically selected to receive pedagogical training and structured opportunities to experience science teaching. Perceptions of teaching science, teaching self-efficacy, and interest in science teaching careers were measured before and after completion of the program using the STEBI-B instrument. Results were counterintuitive but informative. The teaching self-efficacy scores of participants decreased after instructional experiences with younger students.