Capturing Chemical Identity Thinking

Abstract

Chemical identity, the idea that every substance has at least one property that makes it unique and able to be differentiated from other substances, is core to the practice of chemistry. Such practice requires using properties to classify as well as to differentiate. Learning which substance properties are productive in chemical identity thinking is not easy, however, because many features of substances compete for a learner’s attention. Assessments that utilize open-ended questions can reveal ways that students use chemical identity thinking to classify and differentiate substances. On the basis of our previously published hypothetical learning progression of chemical identity, we developed a set of four open-ended questionnaires, which can be used to uncover students’ chemical identity thinking. In attending to literature on the development of qualitative research instruments, as well as design-based instructional materials development frameworks, a four-phase process of development was generated that integrally considers four sets of stakeholders: students, teachers, educational researchers, and disciplinary experts. The development process is described, with attention to previously established criteria for quality in qualitative research. On the basis of stakeholder input and the development process, recommendations are offered for the use of the resulting Chemical Substance Identification (CSI) Survey in classrooms, and the instrument and sample responses are provided.

Probing the Relevance of Chemical Identity Thinking in Biochemical Contexts

“…Although there were eight themes of CI thinking revealed in the responses to the CSI Survey (Ngai and Sevian, 2017), the CE responses did not elicit the same range. A variety of reasons might have contributed to this outcome.…”

“…CI thinking answers two core questions around this premise: 1) “What is this substance?” (a question of classification), and 2) “How is this substance different from other substances?” (a question of differentiation). CI thinking is composed of three facets: domain-general reasoning; CI-specific knowledge; and the practice of CI, which integrates both knowledge and reasoning (Ngai, 2017).…”

“…The characteristics used to classify and differentiate substances can be submicroscopic or macroscopic, and there can be many chemical characteristics appropriate for establishing CI. The knowledge, reasoning, and practice of using a chemical feature to classify and differentiate substances comprises CI thinking (Ngai, 2017).…”

“…We developed the Chemical Substance Identification (CSI) Survey (Ngai and Sevian, 2017) to characterize how students use CI thinking across a broad range of educational levels, including grade 8 through undergraduate completion. The instrument asks students to classify and differentiate a variety of substances that include solids, liquids, and gases, substances typically studied in biology and chemistry, and substances that are familiar and unfamiliar.…”

“…The instrument asks students to classify and differentiate a variety of substances that include solids, liquids, and gases, substances typically studied in biology and chemistry, and substances that are familiar and unfamiliar. Our analysis revealed eight themes in how students classify and differentiate substances, which we called the “themes” of CI thinking (Ngai, 2017), because they describe the ways in which students use chemistry to answer: What is this substance? The themes are outlined in Table 1.…”