Resumen de Examining an Acid–Base Laboratory Practical Assessment from the Perspective of Evidence-Centered Design
Hongyang Zhang, Donald J. Wink
This paper uses evidence-centered assessment design (ECD) to structure and analyze a laboratory activity where students collect and represent titration curve data to determine acid strength in terms of molarity and dissociation constant. Following principles of multidimensional learning, the activity prompts students to demonstrate knowledge of chemistry concepts related to acid–base titrations, the science and engineering practice of using mathematics, and the cross-cutting concept of patterns. The work involved writing two multidimensional learning performances, themselves elaborated into five distinct evidence statements. In the process of coding, we further differentiated the five evidence statements into 13 components, each aligned with at least one place in the task where students could provide evidence of that component to produce results that describe how frequently the students meet the evidence statements. We describe how the evidence statements and their components give insight into whether the students are demonstrating knowledge, skills, and thinking patterns. The data consisted of laboratory reports and postlab questions of 45 students in a general chemistry course at a large public urban university. We examine the data to address the research questions “How does a process of evidence-centered assessment design with associated learning performances provide a structure for research on how students can demonstrate multidimensional learning about chemistry content knowledge?” and “How does an assessment using evidence-centered design and multidimensional learning provide insight about teaching and assessment of learning about the use of titration curve laboratory data in acid–base chemistry?” The results provide insight into the challenges and opportunities associated with having a rich, deep examination of student multidimensional learning across a two-week laboratory assessment, including the way that grading rubrics can impact whether students fully engage with all aspects of the task. Patterns observed within the student work supported conclusions about the nature of student engagement in disciplinary concepts, the practice of using mathematics, and the use of patterns on acid–base titration tasks. We also develop ways to characterize particular components for whether the component can provide single-dimensional evidence, basic multidimensional evidence by requiring use of a concept or practice as a tool, linked multidimensional evidence because a concept or practice is needed to make sense of the phenomenon in a new way, or integrated multidimensional evidence of the different dimensions working together for sense-making.
