Classification of chemical reactions: Stages of expertise

Abstract

In this study we explore the strategies that undergraduate and graduate chemistry students use when engaged in classification tasks involving symbolic and microscopic (particulate) representations of different chemical reactions. We were specifically interested in characterizing the basic features to which students pay attention when classifying chemical reactions at the symbolic and microscopic levels. We identified the categories that students create when classifying chemical reactions, and compared the performance in simple classification tasks of students with different levels of preparation in the discipline. Our results suggest that advanced levels of expertise in chemical classification do not necessarily evolve in a linear and continuous way with academic training; a significant proportion of undergraduate students, regardless of their level of preparation in chemistry, based their classification schemes on the identification of surface features and failed to create chemically meaningful classes. Students' ability to identify chemically meaningful groups was strongly influenced by their recent learning experiences and their graduate work in chemistry. The level of expertise and the type of chemical representation influenced the number and types of categories created, the nature of the features used to build a class, and the role that these features played during the classification process. Although all of the participants in our study expressed similar levels of unfamiliarity with the microscopic images of chemical reactions, advanced students were more adept at using the available representational features to build chemical meaning. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 771–793, 2008

On the acquisition of abstract knowledge: Structural alignment and explication in learning causal system categories

“…This kind of ''relational shift'' in category understanding -from an early focus on concrete features to a later focus on relational structure -is well-attested in cognitive development (Gentner & Rattermann, 1991;Imai, Gentner, & Uchida, 1994;Richland, Morrison, & Holyoak, 2006), as well as in novice-expert studies of adults (Chi et al 1981;Jee et al, 2014;Proffitt, Coley, & Medin, 2000;Shafto & Coley, 2003;Stains & Talanquer, 2008). Further, there is evidence that analogical comparison can promote this shift from object focus to relational focus (Christie & Gentner, 2010;Gentner et al, 2011;Kotovsky & Gentner, 1996;Namy & Gentner, 2002).…”

Teacher Conceptions and Approaches Associated with an Immersive Instructional Implementation of Computer-Based Models and Assessment in a Secondary Chemistry Classroom

“…More recent work in this domain highlighted knowledge structures and thinking processes involved in classification of submicroscopic and symbolic representations (Stains & Talanquer, 2008). The researchers affirmed that it was expertise in chemistry that determined how students classified chemical reactions at the symbolic and submicroscopic levels.…”

“…Given that chemistry learning is inherently symbolic, difficulties most relevant to the current study included the lack of skills that facilitate translation across different types of representation and transfer from 2D to 3D representations (Wu et al, 2001); absence of interconnections that link macroscopic observations with submicroscopic explanations (Liu & Lesniak, 2006) and submicroscopic events with symbolic representations (Calik & Ayas, 2005;Dori & Hameiri, 2003;Stains & Talanquer, 2008); and lack of coherent understandings that negate conceptual understandings (Adadan et al, 2010;Stevens, Delgado, & Krajcik, 2010). Wu et al (2001) outlined difficulties into three major classifications: (i) the inability of students to extract or ascribe meaning to various levels of chemical representation (ii) distinctions between expert and novice learners where students as novice learners experience difficulties translating across different representations and (iii) difficulties associated with mental transformations which allow students to manipulate 2D and 3D representations-thus decode and rotate and determine depth cues.…”

“…The use of models for chemistry teaching and learning has been cited for its role in facilitating conceptual change and in-depth understanding (Adadan et al, 2010;Liu & Hmelo-Silver, 2009;Wu, Krajcik, & Soloway, 2001); and for the representation of unobservable and abstract phenomena at the macro, submicro and symbolic levels (Ardac & Akaygun, 2004;Dori & Hameiri, 2003;Stains & Talanquer, 2008). Other studies have focused on the distinctive principles, and knowledge creation of mental models versus (Coll & Treagust, 2003;Eilam, 2004) physical models and/or the effects of physical models on the construction of mental models (Williamson & Abraham, 1995); the role of 3D representations and visuospatial ability (Barab, Hay, Barnett, & Keating, 2000;Wu & Shah, 2004) and affective outcomes of using dynamic representations in the science classroom (Yalcinalp, Geban, & Ozkan, 1995).…”

The influence of expertise on essence beliefs for mental and medical disorder categories

“…For example, while novices sort fish based on similarity of appearance, commercial fisherman group them according to behavioral and causal relations (Shafto & Coley, 2003; see also, Medin et al, 2006;Proffitt, Coley, & Medin, 2000). Similarly, experts classify chemical reactions by common chemical mechanisms instead of by concrete surface features (Stains & Talanquer, 2008). Novice groups sort real-world phenomena primarily by domain while expert groups in the physical sciences sort by causal category (Rottman, Gentner, & Goldwater, 2012).…”