With the growing emphasis being placed upon situated learning theory, designs increasingly implement problem-based learning (PBL) in various educational contexts. However, some of the difficulties instructional designers face include interweaving elements such as breadth, depth, and situated knowledge in a contextualized learning task. This design case details how the 3C3R method was systematically employed to design a PBL learning environment that highlights the effects of environmental toxins on human fertility. We also discuss how a case library learning environment (CLLE) was implemented and designed to support the decision-making process. This design case examines the challenges involved, such as misunderstandings between the SMEs and instructional designer as we contextualized complex issues related to human biology. A discussion of how we designed for multiple solution paths is also included. Lastly, we discuss the challenges of interweaving the ill-structured problem with multiple narratives found in a case library.Andrew A. Tawfik is an assistant professor of Instructional Design and Technology at Concordia University Chicago where he serves as an instructor of educational technology. He earned his PhD in Learning Technologies from the University of Missouri. Tawfik's research interests include problembased learning, case-based reasoning, case library instructional design, and computersupported collaborative learning. Rebecca J. Trueman is an Assistant Professor of Biology atConcordia University Chicago where she teaches Biology for both non-science and science majors. Rebecca holds a PhD from the University of Illinois at Chicago in Biology. Recently, she has been developing educational technology to enhance the understanding of science. Her work has been funded by the National Science Foundation.Matthew M. Lorz is the Chief Technology Officer of Sustainable Environments LLC. Matt has spent many years involved with research that attempts to detangle anthropogenic effects on ecosystems. His background in the arts has assisted in the development of creative, interesting and accessible cases for case-based reasoning studies. ConteXtThis case details an instructional design project that aimed to redesign an undergraduate Biology module into a problem-based learning activity. The instructor (SME-instructor) wanted to enhance the application of critical thinking skills to the student's examination of the biological world around them. The SME-instructor commented that because her students were non-science majors, they might never have exposure to scientific concepts in an academically rigorous setting outside of her class. Furthermore, the SME-instructor found that students were unable to assimilate all of the varied scientific concepts and research that connected environmental pollutants with infertility in humans. The SME-instructor told the instructional designer that students would often fail to recognize how to apply their textbook readings during problem-solving activities in previous iterations of the ...