Seeing and Modeling Ecosystem Functionality Across Aquatic Ecologies

• In Event: Representing and Supporting the Development of Epistemic Practices in Classroom Communities

Abstract

A key disciplinary practice of ecologists is seeing systems from a functional perspective: organizing large-scale dynamics around important functions rather than individual structures (e.g., Hmelo-Silver, Marathe, & Liu, 2007). However, the richness of ecological contexts can make functionality difficult to decipher (Grotzer & Basca, 2003; Magntorn & Hellden, 2007). Regardless, research on modeling approaches to inquiry (e.g., Lehrer, Schauble, & Lucas, 2008) demonstrates that important ecological concepts are within the grasp of students when instruction arranges for system relationships to become visible. Here, we elucidate how sustained modeling experiences support the practice of generating and extending models of ecosystem functionality.

This design study explored the interplay between student work in two different aquatic ecologies. These investigations purposefully overlapped so work in one could bootstrap the other, mirroring how ecologists reason about similar functionalities across divergent systems (Slobodkin, 2003). Throughout the year, students in a sixth grade class from an urban public school took monthly trips to study a river. Beginning in January, they also designed and manipulated model aquaria, engaging in powerful disciplinary work (Pickering, 1995) to answer individual research questions about dynamics of aquatic ecologies. The design of both investigations emphasized fundamental components of modeling we conjectured would support seeing functional relationships: forming questions, highlighting invisible features, developing measures, and learning from comparisons. Our analysis used individual, semi-structured post-instruction interviews to characterize students’ mental models of system functionality in their aquaria and explore the interplay between the aquaria and river investigations. We also purposively selected three cases, representing a range in mental model complexity, to illustrate the relationship of our design to students’ developing practice, drawing data from interviews, journals, and other class records.

Students developed sophisticated mental models that reflected how their aquaria functioned as a system and included complex causality. The comparative river and aquaria contexts appeared to support students’ developing understandings as students often employed the same set of structures, functions, and relationships in explaining each system and their connections (Table 1). Most considered the aquaria to be good models of the river. However, a few argued against using the aquaria as models, pointing out divergent features of the systems that served similar functions. Despite developing strong structure-function relationships, overall, students did not abstract the general functional group mappings (e.g., privileging oxygenation as a function, therefore seeing oxygenation by aquaria plants as modeling the rivers’ water movement,) characteristic of disciplinary expertise (Slobodkin, 2003). Design elements such as the foci of individual students’ research and learning from comparisons seemed significant in shaping students’ practice seeing and modeling functionality.

Students exhibited forms of reasoning that might be leveraged to support a functional group perspective, in particular their ability to identify multiple structural causes of specific functions and to map functions across ecosystems. We suggest that further design iterations focus on developing norms that encourage students to recruit these resources when drawing comparisons within and between systems, first formally in research meetings and then informally during observations, as a means to amplify their perception of functional similarities across ecologies.

Authors

• Michelle Cotterman, Vanderbilt University

• Richard Lehrer, Vanderbilt University

• Leona Schauble, Vanderbilt University