Date of Award


Degree Type


Degree Name

Doctor of Philosophy in Biological and Environmental Sciences


Sustainable Agriculture and Food Systems


Nutrition and Food Sciences

First Advisor

Geoffrey W. Greene


Statement of the Problem: The need for agricultural science students to graduate from institutions of higher education with strong critical thinking skills is expressed by both educators and employers to respond to the need for strong problem-solving, decision making, and analytic skills in the 21st century. To prepare students for the changing workforce evidence-based instructional practices, such as problem-based learning, need to be implemented into college courses to increase critical thinking skills. However, there are many barriers associated with implementing these teaching practices such as time barriers, large classes, and the challenge of measuring outputs related to critical thinking. The purpose of this dissertation was to understand how the addition of a contextual framework to an online nutrition module influences college students’ critical decision making (CDM). The aims of this paper are to 1) describe the role evidence-based instructional practices have on critical thinking skills in agricultural courses, 2) develop a guided scoring system to measure CDM, and 3) assess how two online modules using problem-based learning and scaffolding facilitate CDM when distributed in large introductory level classes. Methods: This research occurred in two phases, the first phase included the development of the online modules and testing of the reliability of the scoring system. Phase two was comprised of a randomized-control trial where differences in CDM scores were evaluated between groups. The development of the two modules was guided by constructivism, using a problem-based learning and scaffolding approach. A contextual framework was created which included: framing the topic in the form of a question, organizational activities, and support in forming a decision. The guided scoring system was designed using a previously developed rubric to assess critical thinking when making a decision about food choices. The rubric was transformed into a guided scoring system to assess whether students 1) made a decision, 2) used evidence to support their decision, and 3) addressed the opposing point of view. For phase two, students were individually randomized into the intervention group with a contextual framework or the control group without the framework. The modules focused on two topics related to environmentally conscious eating (protein sources and organic foods). Groups were exposed to the same instruction, shown two identical videos, and asked to make a decision about each issue. Summary of Results: Based on phase one, the results showed that the scoring system was reliable, and the modules were successful in promoting CDM. Overall, the CDM framework was found to be successful at encouraging decision making and using evidence to support the decision. The changes in score were captured through the guided scoring system. In phase two, the results give evidence that providing a contextual framework helps students utilize CDM skills. Future interventions should consider using the CDM framework when aiming to increase CDM.



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