As with all learning theories, there are advantages and limitations when creating or implementing problem based learning curriculum. Since this grand experiment in medical education began, strong opinions have been expressed and questions raised about the wisdom, effectiveness and educational efficiency of a tutorial, problem-based, caseoriented approach to teaching the sciences basic to medicine. Unfortunately, many of those arguments have been grounded in emotion, tradition, faculty perceptions and faculty preferences rather than upon a careful analysis of the costs in dollars and human resources versus the benefits of a PBL curriculum.
Students’ interest and benefit
Students appear to enjoy the PBL format more and become more actively involved in their own learning (Antepohl and Herzig, 1999). Reports of the benefits of this type of instructional methodology on student performance on national licensing examinations vary greatly from showing that no harm was done by moving to a PBL curriculum to reports of improved performance for students involved in a PBL curriculum (Verhoeven et al., 1998). This discrepancy in outcomes may be related to limitations in some of the study designs (Albanese and Mitchell, 1993) or variations in the methods used to implement a PBL curriculum.
Faculty workload
PBL-based curriculum is no more labor-intensive than a traditional one. It is simply a matter of utilizing the same amount of human resources, but in a different way (Mennin and Martinez, 1986).
Retention of knowledge
Problem-based learning students may not perform as well on multiple-choice tests as students taught by lecture-based instruction; however, follow-up studies completed by
Norman and Schmidt (1992) reveal better long-term knowledge retention for PBL students.
Motivation:
PBL does provide a more challenging, motivating and enjoyable approach to education.
That may be a sufficient raison d'ệtre, providing the cost of implementation is not too great (Norman and Schmidt, 2000).

Emphasis on Meaning, Not Facts
Most students retain and use little of what they memorize in classroom situations.
Unfortunately, memorization is a common occurance in traditional programs (Vernon &
Blake, 1993). Problem based learning attempts to break this focus by engaging students in structuring solutions to real life, relevant, contextualized problems. By replacing lectures with discussion forums, faculty mentoring, and collaborative research, students become actively engaged in meaningful learning.
Increased Self Direction
As students pursue solutions to their classroom problem, they tend to assume increased responsibility for their learning. These students use self-selected resources, such as journals, on-line searches, and other library resources (Vernon & Blake, 1993), and textbooks, journals, and discussions (Albanese & Mitchell, 1993) more often than traditional students. They also alter their view of instructors from a sourse of test answers to a possible resourse to solving relevant problems (Aspy, Aspy, & Quimby, 1993).
Together, these processes and learning skills help students become more competent in information-seeking skills than traditional students.
Higher Comprehension and Better Skill Development
Problem based learning provides more meaning, applicability, and relevancy to classroom materials. When problems are engaging, difficult, and useful, higher levels of comprehension and skill development occur than in traditional instruction (Albanese &
Mitchell, 1993). Real-world contexts and consequences not only allow learning to become more profound and durable, but increases the transferability of skills and knowledge from the classroom to work (Gallagher, Stepien, & Rosenthal, 1992). This transferability is increased because students are able to practice the knowledge and skills in a functional context, allowing students to better imagine what it will be like using the knowledge and skills on the job (Bridges, 1992).
Interpersonal Skills and Teamwork
Few people in society work in isolation. Because social interaction is such an important aspect of work life, problem based learning incorporates collaborative teams in the solving of relevant problems. This methodology promotes student interaction and teamwork, thereby enhancing students' interpersonal skills (Bernstein et al., 1995; Pincus,
1995; Vernon, 1995) such as working with group dynamic, peer evaluation, and how to present and defend their plans (Delafuente, Munyer, Angaran, & Doering, 1994).
Self-Motivated Attitude
Researchers have found that students generally favor problem based learning classes, and therefore demonstrate increased attendance and attitudes than traditional classes (Vernon
& Blake, 1993). Students think problem based learning is a more interesting, stimulating,

and enjoyable learning method, and that it offers a more flexible and nurturing way to learn. Students in these classes are often less threatened by their environment and more able to pursue learning independent. Taken together, these attitudes help students increasingly become more self-motivated (Vernon, 1995) and independent learners, which help students continue their learning practices once they leave school (Aspy et al.,
1993).
Facilitator-Student Relationship
Faculty who have worked in both traditional and problem based learning formats generally favor problem based learning (Albanese & Mitchell, 1993; Vernon, 1995;
Vernon & Blake, 1993). The aspect faculty liked most is the tutor-student relationship
(Vernon, 1995). Other aspects faculty deem important is an increase in student motivation, group atmosphere, student-directed learning, and student problem solving
(Vernon, 1995). Faculty also consider problem based learning a more nurturing and enjoyable curriculum, and believe the increased student contact is beneficial to the cognitive growth of the student (Albanese & Mitchell, 1993).
Level of Learning
Evaluations done in the medical field indicate that students taught through problem based learning master content as well as students in the traditional courses. (Aspy et al., 1993).
Problem based learning students scored higher on the NBME II & III (clinically-oriented standardized exams) than students in traditional courses.. These students demonstrated better clinical performance and residency programs (Mennin, Friedman, Skipper,
Kalishman, & Snyder, 1993, Vernon & Blake, 1993). Problem based learning medical students also score better than traditional students with respect to learning skills, problem-solving, self-evaluation techniques, data gathering, behavioral science, and their relation to the social-emotional problems of patients (Albanese & Mitchell, 1993).
Why is there an increase in scores resulting in problem based learning? Information theory links three conditions to subsequent improved retrieval and use. It appears that students improve their comprehension because they: (a) are better at activating prior knowledge, (b) learn in a context resembling their future context, and (c) elaborate more fully on the information presented (Bridges & Hallinger, 1991). Increased elaboration promotes mental processing, understanding, and recall. Because content is learned in context, definitions, information, theories, correlations, and principles are learned and integrated with one another (Mandin, Harasym, & Watanabe, 1995).

Academic achievement
Few academicians doubt the ability of students schooled in problem based learning to exhibit strong reasoning and team building skills. Concern has been raised, however, over the breadth of content covered. Because the focus of problem based learning centers on a specific problem, academic achievement scores often favor traditional teaching methods when standardized test are used, but favor neither method when non-standardized forms of assessment are employed (Vernon & Blake, 1993). These measures include problemsolving ability, interpersonal skills, peer-faculty relationships, the ability to reason, and self-motivated learning. In contrast, traditional instruction is judged better in the coverage of science content areas (Albanese & Mitchell, 1993, Vernon, 1995) and in evaluating students knowledge content.
Also, students sometime find difficulty building up layers over layers of knowledge from simple to sophisticated as the case in traditional instruction. In PBL, students gather only what is relevant from knowledge to solve their problem.
Although problem based learning tends to reduce initial levels of gaining knowledge, it improves long-term retention (Farnsworth, 1994).
Time demands
Although students generally favor problem based learning courses, and their ability to solve real-life problems appears to increase over traditional instruction, instructors have not resoundly supported the movement toward this type learning. Contributing to this divergence is the time requirement placed upon faculty to assess student learning
(Delafuente, Munyer, Angaran, & Doering, 1994; Vernon, 1995), prepare course materials, and allow students to complete the reduction in coverage of course material due to the inefficiency of problem based learning.
Role of the student
An unanticipated problem with problem based learning is the traditional assumptions of the student. Most students have spent their previous years assuming their teacher was the main disseminator of knowledge. Because of this orientation towards the subject-matter expertise of their instructor and the traditional memorization of facts required of students, many students appear to have lost the ability to "simply wonder about something"
(Reithlingshoefer, 1992). This is especially seen in first year students who often express difficulties with self directed learning (Schmidt, Henny, & de Vries, 1992).
Role of the teacher
Instructors in problem based learning curriculum need to alter their traditional teaching methods of lectures, discussions, and asking students to memorize materials for tests. In

problem based learning, the instructor acts more as a facilitator than disseminator of information. As such, instructors focus their attention on questioning student logic and beliefs, providing hints to correct erroneous student reasoning, providing resources for student research, and keeping students on task. Because this role will be foreign to some teachers, they may have trouble breaking out of their past habits.
Appropriate problems
Generating the proper question is the most critical aspect of PBL. Without problems that encompass both a large goal and specific objectives which students must find on their way to reaching the goal's solution, there is a good chance that important information will not be studied. In a study that correlated student directed study and faculty objectives, it was found that students did not stay on track and many important objectives were omitted
(Dolmans, Gijselaers, & Schmidt, 1992). It has even been speculated that if students divert from their anticipated directions during their solution generation, they may completely miss the main content if not redirected by their instructor (Mandin, 1995).
Problem Formulation is a science and a skill that could be either there or not, and here comes the problem.
Student assessment
Problem based learning differs from traditional instruction in a variety of ways, and therefore student knowledge and achievement may be better measured with alternate assessment methods. These methods include written examinations (like modified essay questions), practical examinations, concept maps, peer assessment, self assessment, facilitators/tutor assessment, oral examinations (like triple-jump exams and oral presentations), and written reports.
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