Supporting Mechanistic Reasoning in Domain-Specific Contexts

Abstract

Mechanistic reasoning is an epistemic practice central within science, technology, engineering, and mathematics disciplines. Although there has been some work on mechanistic reasoning in the research literature and standards documents, much of this work targets domaingeneral characterizations of mechanistic reasoning; this study provides domain-specific illustrations of mechanistic reasoning. The data in this study comes from the Assessment of Mechanistic Reasoning Project (AMRP) (Weinberg, 2012), designed using item response theory modeling to diagnose individuals' mechanistic reasoning about systems of levers. Such a characterization of mechanistic reasoning illuminates what is easy and difficult about this form of reasoning, within the subdomain of simple machines. Moreover, this work indicates how domain-general principles may be limited. The study participants included elementary, middle, and high school students as well as college undergraduates and adults without higher education. Although the majority of participants responded to the AMRP by diagnosing at least one mechanistic element (elements inherent to the working of systems of levers) as they predicted its motion, such reasoning was not trivial. In fact, the diverse reasoning by participants shows how systems of levers support elements of mechanistic reasoning. Moreover, this study provides evidence that the development of mechanistic reasoning is dependent on domainspecific experience.

Assessing Mechanistic Reasoning: Supporting Systems Tracing

“…Five items were indicated in each form that elementary and middle school students were instructed to skip in order to avoid interview fatigue. Using item difficulty estimates from a previous study (Weinberg, 2017b), those items that were skipped by elementary school students did not have different mean item difficulty estimates (M 5 20.03 logits) from those that were not skipped (M 5 20.08, one-tailed t-test). Thus, the assessment was identically difficult for all age groups.…”

“…The construct was also informed by literature about the difficulty individuals have reconciling their intuitions about causality with forms of mechanistic explanation valued by disciplines (Abrams & Southerland, 2001;Chin & Brown, 2000;Hmelo-Silver & Pfeffer, 2004;Talanquer, 2010). Finally, the construct addressed what participants find difficult when reasoning about simple mechanical systems (Bolger et al, 2012;Lehrer & Schauble, 1998;Metz, 1985;Weinberg, 2017b). This analysis resulted in a distinct construct focusing on mechanistic reasoning about systems of levers; this construct level has been called mechanistic tracing.…”

“…The participant groups that comprise the sample are presented in Table 2. As described in Weinberg (2017b), the elementary, middle, and high school students came from public and private schools in the southeastern USA. The university undergraduates came from three universities, two in the southeastern and one in the midwestern USA.…”

“…The easiest item is Sequential Tracing-A39 (STA39) (Figure 3), with a mean item difficulty of 20.76 logits. Weinberg (2017b) reported that the following machine characteristics impact participants' diagnosis and causal connection of a machine's mechanisms: (a) item type, (b) number of levers, (c) lever type (e.g., class 1 levers), (d) arrangement of levers, and (e) the presence of specialized and unfamiliar levers (e.g., a bent crank). The number of levers, arrangement of levers, and inclusion of a bent crank are not independent machine characteristics.…”

“…Reasoning about mechanism is foundational to disciplined inquiry in science and engineering; thus, it should be one of the foundations of a science, technology, engineering, and mathematics (STEM) education (Bolger, Kobiela, Weinberg, & Lehrer, 2012;National Research Council [NRC], 2011; Russ, Scherr, Hammer, & Mikeska, 2008;Weinberg, 2017aWeinberg, , 2017b. The NRC (2009) indicates the tight connection between engineering principles, disciplinary knowledge, and disciplinary practices (e.g., mechanistic reasoning).…”