<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>About the case:</i></b> We suggest using Aristotle's rhetorical triangle, a tool for analyzing communication in terms of logos (logic), pathos (values), and ethos (identity), in science, technology, engineering, and mathematics (STEM) undergraduate classes. We investigate how the triangle can enhance students’ communication skills by developing awareness of pathos and ethos, and shed light on values, considerations, and professional identity at different stages of their studies. <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>Situating the case:</i></b> Developing communication skills among STEM students is imperative even in the age of AI-based tools. Although many books and platforms exist to help facilitate communication in general, STEM students require practical tools to foster the rhetorical skills needed for effective and persuasive communication. <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>Methods:</i></b> The rhetorical triangle intervention was implemented in two undergraduate courses to help students develop the other necessary elements of effective communication beyond logos: i.e., pathos and ethos. <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>Results:</i></b> Our results show that the intervention enhanced students’ ability to express shared values (pathos) with their audience and fostered the development of professional identity (ethos). Our findings also revealed notable differences in professional identity expression when comparing two different samples of future scientists and engineers in their freshmen and senior years. <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>Conclusion:</i></b> We suggest that incorporating the elements of the rhetorical triangle into STEM education can enhance students’ communication skills, particularly in expressing the value of their work and developing a strong professional identity. We recommend integrating these elements throughout various stages of the curriculum to deepen students’ understanding of effective communication and persuasion.