The Role Of Diagnostic Reasoning In Engineering Design: Case Studies

Abstract NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Case Studies on the Role of Diagnostic Reasoning in Engineering Design Introduction Design activities have been used in K-12 classes to contextualize student learning of STEM ideas, to raise interest in difficult-to-teach topics, and as transfer tasks to test student understanding. One of the enduring conundrums in engineering design is that designers, regardless of level of experience, can end up with final products that look remarkably similar to their first sketches or prototypes. A number of explanations for this problem, which has been dubbed “functional fixedness” (Cross, 2000) and “idea fixation” (Sachs, 1999), have been proposed for this phenomenon where little seems to get learned or gained through cycles of design iterations. One hypothesis that this study investigates is the notion that idea fixation, especially when done by beginning designers, is simply due to the novices not noticing weaknesses in their current plan or prototype. If all looks well with a prototype or product that performs poorly during testing, there then would be no driving force to change the current design. The lack of capability to notice problems in a sketch, prototype or product may be related to the little studied role of diagnostic reasoning in engineering design. A review of the existing literature suggests that to diagnose and troubleshoot the systems they are planning, designers need a number of ideas and cognitive tools to do the job. Such a conceptual model may include (1) an understanding of systems; (2) relevant device knowledge and (3) relevant domain knowledge, such as how the device or system works; (4) topographic knowledge (Rasmussen, 1984) that amounts to a mental map of the product or system’s physical layout, and (5) and an understanding of procedures for doing troubleshooting and testing hypotheses about possible faults (Jonassen & Hung, 2006). For science teachers using design tasks, domain knowledge would include the science and engineering principles that explain basic product functions (e.g., Hooke’s Law for return springs; Newton’s Laws of Motion for vehicle or projectile motion). While such understandings by themselves are thought not to be sufficient for doing effective fault diagnosis (Jonassen & Hung; Morris & Rouse, 1985), they may enable practitioners more effectively to transfer their diagnostic and troubleshooting skills to new situations (MacPherson, 1998). In the context doing engineering design, diagnostic reasoning involves in part the zooming in and out of attention in order to investigate the various levels of system performance. Such attentional focusing can help the practitioner isolate faults, which can reduce the complexity of the system being considered, lessens the load on working memory, and in turn improve troubleshooting performance (Axton, Doverspike, Park & Barrett, 1997). When designing, flaws that get detected via diagnostic reasoning can also inspire ideas for new features or as-yet unthought of systems. As in scientific discovery, noticing unexpected properties or behaviors during testing can be a powerful impetus for conceptual change (Kolodner & Wills, 1996). This paper’s working hypothesis is that diagnostic reasoning is critical for students to notice flaws in their designs, change them and so improve the quality of their final products through the process of iterative design. Teaching students diagnostic reasoning in the context of doing technological or engineering design can become an authentic context in K-12 settings for: