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Problem-based learning (PBL) is a student-centered instructional strategy in which students collaboratively solve problems and reflect on their experiences. It was pioneered and used extensively at McMaster University in Canada.

PBL is based on the educational theories of Vygotsky, Dewey, and others, and is related to social-cultural and constructivist theories of learning and instructional design.

Characteristics of PBL are:

• Learning is driven by challenging, open-ended, ill-defined and ill-structured problems.
• Students generally work in collaborative groups.
• Teachers take on the role as "facilitators" of learning.

In PBL, students are encouraged to take responsibility for their group and organize and direct the learning process with support from a tutor or instructor. Advocates of PBL claim it can be used to enhance content knowledge and foster the development of communication, problem-solving, and self-directed learning skill.

PBL positions students in simulated real world working and professional contexts which involve policy, process, and ethical problems that will need to be understood and resolved to some outcome. By working through a combination of learning strategies to discover the nature of a problem, understanding the constraints and options to its resolution, defining the input variables, and understanding the viewpoints involved, students learn to negotiate the complex sociological nature of the problem and how competing resolutions may inform decision-making.

Support systems, which include resources germane to the problem domain as well as instructional staff, are provided to scaffold students skills "just in time" and within their learning comfort zone (Vygotsky's Zone of Proximity).

Evidence supporting problem-based learning

Hmelo-Silver, Duncan, & Chinn cite several studies supporting the success of the constructivist problem-based and inquiry learning methods. For example, they describe a project called GenScope, an inquiry-based science software application. Students using the GenScope software showed significant gains over the control groups, with the largest gains shown in students from basic courses. 

Hmelo-Silver et al. also cite a large study by Geier on the effectiveness of inquiry-based science for middle school students, as demonstrated by their performance on high-stakes standardized tests. The improvement was 14% for the first cohort of students and 13% for the second cohort. This study also found that inquiry-based teaching methods greatly reduced the achievement gap for African-American students. 

A systematic review of the effects of problem-based learning in medical school on the performance of doctors after graduation showed clear positive effects on physician competence. This effect was especially strong for social and cognitive competencies such as coping with uncertainty and communication skills. 

Examples of applying Problem-Based Learning pedagogy to curriculum

 In Malaysia, an attempt is being made to introduce a hybrid of problem-based learning in secondary mathematics called PBL4C, which stands for problem-based learning the four core areas in the mathematics education framework. These core areas are mathematics contents, thinking processes, skills, & values, with the student as the focus of learning. This hybrid first sprouted in SEAMEO RECSAM in 2008. 

At tertiary level, many Malaysian universities are going for PBL purposely to improve the quality of the graduates produced. In collaboration with Aalborg University of Denmark, PBL was introduced at University Tun Hussein Onn Malaysia (UTHM). Since then the PBL was widely used among engineering and as well as humanities lecturers at UTHM (Berhannudin, 2007).

Several medical schools have incorporated problem-based learning into their curricula, using real patient cases to teach students how to think like a clinician. More than eighty percent of medical schools in the United States now have some form of problem-based learning in their programs. Research of 10 years of data from the University of Missouri Medical School PBL curriculum supports PBL. ( Koh GC-H, Khoo HE, Wong ML, Koh D. The Effects of Problem-based learning during medical school on physician competency: a systematic review. CMAJ 2008;178(1):34-41.)

Constructivism and PBL

From a constructivist perspective Problem-based learning (PBL), the role of the instructor is to guide the learning process rather than provide knowledge (Hmelo-Silver & Barrows, 2006). From this perspective, feedback and reflection on the learning process and group dynamics are essential components of PBL. Students are considered to be active agents who engage in social knowledge construction.

Criticisms of Problem-Based Learning

Problem-based learning and cognitive load

Sweller and others have published a series of studies over the past twenty years that is relevant to problem-based learning but concerning cognitive load and what they describe as the guidance-fading effect (Sweller, 2006). Sweller, et al. conducted several classroom-based studies with students studying algebra problems (Sweller, 1988). These studies have shown that active problem solving early in the learning process, is a less effective instructional strategy than studying worked examples (Sweller and Cooper, 1985; Cooper and Sweller, 1987). 

Certainly active problem solving is useful as learners become more competent, and better able to deal with their working memory limitations. But early in the learning process, learners may find it difficult to process a large amount of information in a short amount of time. Thus the rigors of active problem solving may become an issue for novices. Once learners gain expertise the scaffolding inherent in problem-based learning helps learners avoid these issues. These studies have however been conducted largely based on individual problem solving of well-defined problems.

Sweller (1988) proposed cognitive load theory to explain how novices react to problem solving during the early stages of learning. Sweller, et al. suggests a worked example early, and then a gradual introduction of problems to be solved. They propose other forms of learning early in the learning process (worked example, goal free problems, etc.); to later be replaced by completions problems, with the eventual goal of solving problems on their own (Sweller, Van Merrienboer, & Paas, 1998). This problem based learning becomes very useful later in the learning process.

Many forms of scaffolding have been implemented in problem based learning to reduce the cognitive load of learners. These are most useful to fade guidance during problem solving. As an example, consider the fading effect helps learners to slowly transit from studying examples to solving problems. In this case backwards fading was found to be quite effective.

Cognitive effects of problem-based learning

The acquisition and structuring of knowledge in PBL is thought to work through the following cognitive effects (Schmidt, 1993):

• initial analysis of the problem and activation of prior knowledge through small-group discussion
• elaboration on prior knowledge and active processing of new information
• restructuring of knowledge, construction of a semantic network
• social knowledge construction
• learning in context
• stimulation of curiosity related to presentation of a relevant problem