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An example of scaffolds to facilitate science learning strategies

The following is a short discussion about instructional scaffolds that we have adapted and expanded in our projects, called the Model-Evidence Link (MEL) diagram. The original structure and mode of the MEL was developed by a team of educational psychologists, learning scientists, and science education researchers at Rutgers University (see Chinn & Buckland, 2012, for an overview). Lombardi and colleagues (Lombardi, Bailey, et al., 2018; Lombardi, Bickel, et al., 2018; Lombardi, Sinatra, & Nussbaum, 2013) discuss the adaptations and expansions that we made to the MEL in some detail, and we highlight some of the MEL features in the following discussion. However, prior to discussing the MEL, we enthusiastically acknowledge and support similar efforts of other researcher teams who are developing or have developed instructional scaffolds that facilitate argumentation and/or science as modeling strategies (e.g., Quality Talk in Science, Murphy et al., 2018; Promoting Reasoning and Conceptual Change in Science, Chinn, Duncan, & Rinehart, 2018).

The MEL is an instructional scaffold that facilitates students’ scientific evaluations about the connections between multiple lines of scientific evidence and alternative explanatory models about an observed phenomenon (Figure 11.1; Holzer, Lombardi, & Bailey, 2016; Lombardi, 2016). In the context of a particular topic (e.g., causes of current climate change, the link between fracking and earthquakes, the role of wetlands in ecosystem services, and formation of the Moon), the MEL diagram and associated support activities present students with two conceptual models, each providing an explanation for a phenomenon. For example, in the Wetlands MEL, two models provide competing explanations about how wetlands affect humans and the environment: Model A, where wetlands provide ecosystem services that contribute to human welfare and help sustain the biosphere; and Model B, where wetlands are a nuisance to humans and provide little overall environmental benefit. When using the MEL diagram as a scaffold, students draw arrows in one of four different shapes to indicate their evaluation about how well each line of evidence supports each model. Straight arrows indicate that evidence supports the model; squiggly arrows indicate that evidence strongly supports the model; straight arrows with an “X” through the middle indicate the evidence contradicts the model; and dashed arrows indicate the evidence has nothing to do with the model.

The MEL promotes students’ cognitive and behavioral engagement in several science learning strategies, including science as inquiry, argumentation, and science as modeling. For example, the MEL diagram prompts students to evaluate the connections between line of evidence and two alternative explanatory models about a phenomenon. This allows students to critique explanatory models much like the scientific community does. Researchers and practitioners have given little attention to critiquing of alternatives in science learning; however, “as all ideas in science are evaluated against alternative explanations and compared with evidence, acceptance of an explanation is ultimately an assessment of what data are reliable and relevant and a decision about which explanation is the most satisfactory” (National Research Council, 2012, p. 44). In fact, our empirical studies show that the MEL results in deeper learning when students consider connections between lines of evidence and alternative explanations, over and above when they consider the same lines of evidence and only one alternative (i.e., the scientific explanation; Lombardi, Bailey, et al., 2018; Lombardi et al., 2013).

The inherent mode of critique initiated by the MEL is also related to students’ argumentation and modeling as science strategy use. The NRC (2012) specifically states that “Engaging in argumentation from evidence about an explanation supports students’ understanding of the reasons and empirical evidence for that explanation, demonstrating that science is a body of knowledge rooted in evidence” (p. 44). The MEL expands upon this central notion of argumentation involving claims, evidence, and reasoning in argumentation, by introducing claims, evidence, reasoning, and critique of alternatives. We have examined both students’ depth of reasoning and critique in a task that students complete after drawing their MEL diagram. In this explanation task (Figure 11.2), we prompted students to describe evidence to model links they consider important or interesting. Using a sentence prompt for each explanation, participants indicated the model and evidence number that they chose to discuss, as well as the evidence-to-model connection strength they drew on the diagram (i.e., strongly supports, supports, contradicts, or has nothing to do with). This preface served as the beginning of participants’ written explanations, next prompting evaluation with the word “because.” For example, a full written explanation from one middle school student participant said, “Evidence #1 strongly supports Model A because atmospheric greenhouse gases have been rising for the past 50 years because of humans” (Lombardi, Bickel, Brandt, & Burg, 2017, p. 319). In our iterative and qualitative content analyses of these written explanations, we found four increasing levels of evaluation from erroneous to critical (Lombardi, Bailey, et al., 2018; Lombardi, Bickel, et al., 2018; Lombardi, Brandt, Bickel, & Burg, 2016), with interesting relations between evaluations and learning when students specifically wrote about lines of evidence that contradicted an explanatory model. These results suggest that contradictory evidence is important in changing students’ epistemic judgments (e.g., a plausibility judgment about a particular explanatory model compared to another) to facilitate the process of scientific evaluation in argumentation and collaborative knowledge construction of models (Erduran & Dagher, 2014).

Although our research has shown that the MEL increases students’ use of science learning strategies within the course of the activity, we have not yet been able to ascertain whether students transfer their strategy use outside of the classroom context. Our recent development and testing efforts are examining ways to internalize the MEL scaffold into students’ mental representations, enabling them to transfer their use of scientific and critical evaluations beyond the specific activities. We are purposely incorporating the idea of conceptual agency (Pickering, 1995), where learners who exercise such agency are authors of their own contributions, accountable to the learning community, and have the authority to think about and solve problems

(Nussbaum & Asterhan, 2016). In this newer version of the scaffold, students build their own MEL diagram from a set of lines of evidence and explanatory models. Our hope is that through building and using their own MEL, students will become agents of model evaluation, which is a key component of both the argumentation and science as modeling strategies.

 
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