Community ecology concepts, such as food web complexity, are cornerstones of undergraduate ecology courses. Students are expected to understand food web dynamics and transfer this knowledge across contexts. Variation in framing, i.e., using one or more community examples, is one evidence-based approach proposed to improve knowledge transfer to novel scenarios. An expansive framing approach provides multiple contexts with the idea that students will develop general reasoning about competition, top-down and bottom-up control, and changes in interactions over time. Conversely, a bounded framing approach focuses on in-depth learning of one community.
Our goals were to explore whether instructional framing affects student explanations of food webs and to categorize student sophistication in reasoning about food web dynamics. Undergraduate life science majors (n=20) were assigned to a bounded (1 food web) or expansive (5 food webs) learning session. In a follow-up transfer session, all students were presented with made-up organisms and asked about community interactions, population sizes, and management scenarios. Session transcripts were analyzed using qualitative emergent coding techniques to explore evidence of knowledge transfer and themes in student understanding of food webs.
All students, regardless of framing, explained concepts such as indirect effects and competition and correctly identified food web impacts of changing population sizes. Most students used reasoning that reflected simplistic, linear understandings of food web dynamics, rather than systems thinking. Students who reflected upper level reasoning discussed multiple potential outcomes (n=12) or changes in food web dynamics over time (n=5), or a combination of the two reasoning types. Responses were categorized based on how often and how well students expressed upper level reasoning. Students were categorized as Low if they did not include any upper level reasoning (n=7), Medium if they included one to two instances (n=8), and High if they included three or more instances (n=5). There was a mixture of bounded and expansive students in the Low and Medium categories, and all students in the High category were in the expansive treatment, suggesting that expansive framing helped students achieved a higher level of reasoning sophistication. Framing food webs with multiple examples may assist student in generalizing some upper level reasoning skills compared to limited examples with greater depth. Instructional supports about multiple outcomes, proportional reasoning, and community dynamics over time will likely benefit all students as they are asked to apply their community dynamics reasoning in ecology courses.