The Science on Wheels Peer Mentoring Educational Center (SONW) was established in 1991 at the University of Puerto Rico Mayaguez (UPRM). For the last 24 years, professors, as well as graduate and undergraduate level students have been inspiring K-12 students to pursue STEM careers, and transforming the way that K-12 teachers approach STEM learning. Their approach is based on the Expository Peer Mentoring Model, transferring STEM knowledge and skills through exposure to hands-on scientific experimentation, and enhancement of critical thinking, language and other soft skills. This pipeline becomes an exponential tool in enhancing STEM knowledge and skills in this population. Overall 376 university fellows (247 graduates and 129 undergraduates) have provided general, specific and integrated STEM interventions to 3,334 teachers and 145,290 pre-college students. Since the inception of the program, the ratio of STEM enrolled students at UPRM who have directly interacted with SONW has been consistently higher than those who did not participate in the program.