Integrating science and engineering has become a focal point for current research in science and STEM educational fields. Infusing engineering design as an application of scientific principles is beneficial, as it demonstrates an authentic, real-world application and allows for not only student engagement and enthusiasm, but also an avenue to learn and transfer science skills and content. In order to effectively transfer scientific principles and skills, students must first notice that science principles can inform the design, and then choose to apply those skills through focusing processes. While there has been previous studies that have investigated transfer as part of integrated STEM design challenges, they tend to emphasize physics principles that inform the physical construction of a device. In contrast, chemistry principles are often used to power or perform a function within a constructed device. To date, there have been few studies that have investigated noticing and focusing on chemistry as part of a design heuristic. The design-based action research study that follows addresses this gap by investigating how students notice chemistry using prior inquiry activities to highlight chemistry principles, as well as how students focus on applying those principles as part of design heuristic in a chemistry infused integrated STEM design challenge. A set of twelve focusing processes emerged from the data set. The focusing processes were used to compare two similar design challenges. The study found that the chemistry-infused challenge saw an increase in duration and depth of focus on chemistry deep structure. In addition, a set of three inquiry activities were implemented before the final challenge to highlight the chemistry deep structure necessary. The study found that participants were able to notice the chemistry deep structure from the inquiry activities during the build, and their notice was mediated by the tools available within the problem space. Participants that did not notice could be led to notice through teacher-scaffolding interventions. However, participants would often revert back to a trial-and-error approach when the task became cognitively demanding. The findings are situated within the extant literature and its contributions to the field are discussed in greater detail. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]