While BIM software becomes popular for CAAD and architectural design educations, the affordance of BIM for students' architectural idea developments, called intra-process of communication, is still unknown. Therefore, this study conducted t-test quantitative analysis in order to the scores for feedback, idea productivity, idea development for architectural elements(form, interior space, material, and details), and creative motivation(novelty, appropriateness) using BIM and non-BIM 3D modeler. To achieve the goal, in authentic CAAD class, architecture major students proposed two office designs using those two tools, then they evaluated in which ways those tools influenced their idea developments.