You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Case-Based Learning on Web in Higher Education: A Review of Empirical Research 
Chapter Title:  Introduction 
1. Abstract of Cited Paper (BIB001):  This research project studied the effects of hierarchical versus heterarchical hypermedia structures of web-based case representations on complex problem-solving skills and knowledge assembly in problem-centered learning environments to develop a system or model that informs the design of web-based cases for ill-structured problems across multiple disciplines. Two groups of students were assigned to work through an ill-structured problem, represented hierarchically and heterarchically in a web-based format. A web-based tracking program was deployed to track students' journeys through the hypermedia case designs. Students were observed while interacting with the problem and were interviewed after submitting their case solutions. Results from the tracking program, observations, case solutions, and interview questions will address case design issues, problem-solving issues, and group processes. RESEARCH PROBLEM Several research projects and studies (Booth-Sweeney, 2001; Herreid & Schiller, 2001; Siegel, et al., 2000; Rogers & Erickson, 1998; Gerdes, 1998; Sutyak, Lebeau, & O'Donnell, 1998; Fitzgerald & Semrau, 1996; Jacobson, Maouri, Mishra, & Kolar, 1996) have investigated the use of cases or problems in instruction particularly in relation to case structure (e.g., linear vs. hypertext, narrative vs. conceptual) and problem complexity (e.g., well-defined vs. ill-structured), and the impact of such variables on advanced knowledge acquisition. However to date, there is no explicit framework or instructional model to guide the design of web-based hypermedia cases, particularly for ill-structured problems or learning tasks that require students to engage in complex problem-solving and knowledge transfer. In addition, Grissom and Koschmann (1995) contended that cases or problems that are used as a stimulus for authentic activity are hard to come by in disciplines other than medicine, business, and law, and suggested tha t hypertext/hypermedia may be a more efficient and effective medium to produce cases for learning environments that are problem-centered. This research project studied the effects of different hypermedia structures of web-based case representations on complex problem-solving skills and knowledge assembly in problem-centered learning environments to develop a system or model that informs the design of web-based cases for ill-structured problems across multiple disciplines. Ill-structured problems are the kinds of problems or tasks that are encountered in everyday practice requiring the integration of several content domains and possessing multiple solutions or solution paths (Jonassen, 1997). They are problems that are "situated in and emergent from a specific context" (Jonassen, 1997, p. 68) and "lacking solutions that are indisputably correct" (Kagan, 1993, p. 715). Therefore they are arguably most appropriate for engaging students in authentic activity and assessing complex problem-solving skills and knowledge transfer. THEORETICAL FRAMEWORK Duffy and Cunningham (1996) identified five strategies for using problems in instruction: (a) the problem as an example; (b) the problem as an integrator or test; (c) the problem as a guide; (d) the problem as a vehicle for process; and (e) the problem as a stimulus for authentic activity. This research project focused on their strategy of using the problem as a stimulus for authentic activity. Authentic activity is most simply defined as the ordinary practices of a culture, namely, coherent, meaningful, and purposeful activities (Brown, Collins, & Duguid, 1989). More specifically, an authentic learning task for students should have the following characteristics. It should: (a) cue the leaner to the desired solution(s) in order to promote "free exploration" or self-directed inquiry; (b) allow multiple solutions or solution paths; (c) have no explicit means for determining appropriate action; (d) be perceived as real or consequential by the learner to promote ownership of the problem; and (e) possess multiple criteria for evaluating solutions. …

Literature Review:
When new instructional innovations are introduced to students, they are implicitly or explicitly requested to adjust themselves to the new ways of teaching and learning by their instructors, who believe that new innovations may result in better learning outcomes than the previous approaches . Case based learning instruction is one of the constructivist oriented teaching approach BIB001 since it promotes students' active participation so they could form their own learning. Cases are stories with a message which students analyze and consider the solutions of these stories. The teacher and the students are working together while students have controlled analyzing cases. There are many research studies that related to the cases, used in teaching on the web, allow the students to study better BIB002 . In addition, case-based learning helps transfer knowledge and expectations of the students from their learning. The high level knowledge transfer will be more effective with case-based learning and problem solving on the web   . This is consistent with the findings of who studied the design and development of a case study to enhance learning and problemsolving abilities of students and the study found that the CBL-CMPS enhance students' problem solving. It also can be used in real life as well. Such claims and suggestions, however, have often not been based on empirical studies. This paper reviews the empirical research on Case-based learning on web in higher education to address the question "What does the empirical research indicate about CBL on web" Following a brief description of CBL on web, and common features, we describe our data sources, method of analyses and result findings. In the discussion we focus on directions for future research related to the use of CBL on web in higher education.