Inquiry-based learning has been widely applied in the classroom. Different inquiry learning models may have different orders of performing tasks and discussing. In this study, the Discuss-Do (D-DO) inquiry model and the Do-Discuss (DO-D) inquiry model were applied in the science learning of two groups of fifth-grade students. Group 1 (n = 41) used the Discuss-Do model whereas Group 2 (n = 38) used the DoDiscuss model. Interest measurements and the Light Reflection Test were administered to the two groups prior to and following the experiment to investigate the effects of the two kinds of inquiry model on students' individual and situational interest, and concept achievement through learning the unit of Light Reflection in a science course. Results showed a significant difference in situational interest and concept achievement between the two groups. However, there was no significant difference in the individual interest of the two groups. Findings suggested that the adoption of the Do-Discuss model is more conducive to learners' development of situational interest and concept achievement, which has implications for exploring task order adjustments for inquiry-based learning, as well as in education for science instructors.