Technological/engineering design based learning (T/E DBL) provides a context in which students may utilize content knowledge and skills to develop prototype solutions to real-world problems. In science education, design based science (DBS) utilizes technological/engineering design based approaches in science education as a means for enhancing the purpose of and relevance for scientific inquiry by contextualizing it within the goal of developing a solution to a real-world problem. This study addressed the need to investigate the ways in which students utilize higher order thinking skills, demonstrated through the use of knowledge associated with declarative, schematic, and strategic cognitive demand when in engaged in DBS activities. The purpose of this study was to determine what relationships exist between engagement in DBS and changes in students' depth of understanding of the science concepts associated with the development of design solutions. Specifically, the study determined how students' abilities to demonstrate an understanding of the science concepts, required by assessments of different cognitive demand, change as they were engaged in a design-based science unit associated with heat transfer. Utilizing two assessment instruments, a pre/post-1/post-2 test and content analysis of student design portfolios based on Wells (2012) and utilizing Li's (2001) system to code student responses, the following research question was addressed: What changes in students' science concept knowledge (declarative, schematic, and strategic demand) are evidenced following engagement in design based learning activities? Although the results are not generalizable to other populations due to the limitations associated with the study, it can be concluded that design based learning activities incorporated in science courses can foster higher order thinking. Results from the study suggests that students' abilities to demonstrate their understanding of certain science concepts through higher order thinking, including utilizing concept knowledge strategically in open-ended problem solving, increased following engagement in design based learn activities. Results have implications in technological/engineering design education, in science education, and in integrative STEM education. Implications include the utility of design portfolios as both an assessment instrument and learning tool to ensure that concept knowledge is explicitly connected to and used in the design activity. / Ed. D.