Research on creativity in engineering has expanded, yet empirical evidence remains limited on how creativity develops through secondary school engineering curricula. This qualitative study examined teachers’ perceptions of middle and high school students’ creativity while designing and building chain reaction machines. Using the “Assessing Creativity” framework, deductive analysis of eleven teachers’ interviews revealed students’ creative behaviors across all four categories: (a) generating ideas (e.g., fluency, originality, flexibility), (b) digging deeper into ideas (e.g., synthesizing, resolving ambiguity), (c) openness and courage to explore ideas (e.g., curiosity, imagination, tenacity), and (d) listening to one's “inner voice” (e.g., persistence, self-direction, awareness of creativity). Teachers most frequently reported convergent thinking and traits such as curiosity, openness to experience, and risk-taking. Findings provide preliminary insights into the understanding of creativity in education, suggesting that engineering-design curricula foster creative thinking while preparing students with essential skills required in STEM pathways. © The Author(s) 2025