Evaluating an Interactive Lecture Model for Teaching Complex Numbers: A Comparison With Traditional Instruction

In this paper, an interactive lecture model for teaching complex numbers through coordinated algebraic, geometric, and trigonometric representations is examined. Two existing groups of first-year engineering students received traditional (n = 17) or interactive instruction (n = 24). A common post-test was administered immediately after the 45-minute lecture, followed by a questionnaire in the interactive group. A higher overall mean score was obtained by the interactive group (5.92 versus 4.12 out of 10; p = 0.035, Hedges’ g = 0.66). For the six conversion and coordination questions, the difference was not statistically significant (3.38 versus 2.47 out of 6; p = 0.117). Higher performance was also observed on within-representation questions; therefore, a representation-specific advantage was not established. Attention and active involvement were generally reported, while understanding of relationships among representations was less consistently endorsed. Higher immediate achievement was associated with interactive instruction. Causal conclusions and evidence of lasting differences are limited by non-random group assignment and assessment after a single lecture.