Initiatives to integrate engineering design in the elementary science classroom have become increasingly evident in both national reform documents and classroom practice. Missing from these efforts is a purposeful attempt to capture students' designerly thinking and dialogues as they engage in the process. The purpose of this study was to investigate how elementary school students approach and engage in engineering design using concurrent think-aloud protocols. Data from seven concurrent think-aloud protocols among triads of elementary students across seven classrooms were analyzed to identify how students conceptualize design. Researchers employed a transfer problem and think-aloud protocol analysis to assess students' transfer of learning from classroom science based engineering design-based experiences. Results indicate that elementary student triad design teams were able to define a design problem, identify constraints and criteria, and generate multiple design ideas to solve the problem. Protocol timelines were generated using NVivo software to capture sequence of the triads' coded cognitive strategies crucial in understanding which triads used a systematic approach to solving the problem from triads that randomly brainstormed ideas. If design is to become a pedagogical approach to teaching science or other STEM-related subjects, attention must be given to how students learn design and function within design. Concurrent think-aloud protocol provides a promising means of assessment of such efforts.