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,Hamilton,Ontario,Canada. Characteristics of PBL are:
- Learning is driven by challenging, open-ended problems.
- Students work in small collaborative groups.
- Teachers take on the role as “facilitators” of learning.
Accordingly, 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.
Presenting problems to learners
Problem-based learning (PBL) is typically organized with small groups of learners, accompanied by an instructor, faculty person, or facilitator. During this process, a series of problems are provided to learners with guidance early in the PBL process (with introductory problems), and then later guidance is faded as learners gain expertise (Merrill, 2002). Guidance is faded as group members feel more confident with the subject matter and become more competent with the learned procedures.
Merrill (2007)  suggests beginning with worked examples and then later, introduce students to smaller less complex problems. But as the process progresses, Merrill suggests changing problems by adding components to make them more realistic (Merrill, 2002, 2007). Thus it is important to begin with simplified versions of real world problems to progressively add components. This progression and fading motivates learners as they slowly gain expertise and take ownership.
During the PBL process learners should discuss problems, define what they know, generate hypotheses, derive learning goals and organize further work. Results may be subsequently presented to larger groups (under guidance from an instructor). A PBL cycle should conclude with learners reflecting on the learning that has taken place.
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.
Problem-based learning and cognitive load
Sweller and many 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 and his associates 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.
Sweller (1988) proposed cognitive load theory to explain how novices react to problem solving during the early stages of learning. Sweller and his associates 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
Some theories suggest that learning occurs as students collaboratively engage with concepts in meaningful problem solving. In this view, knowledge is seen as a tool for thinking and for enabling learners to participate in meaningful activity.
Problem-based learning is often referred to as a form of Inquiry-based learning (IBL), which describes an environment in which learning is driven by a process of inquiry owned by the student.
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.
Executing Problem-Based Learning pedagogy to curriculum
Republic Polytechnic (RP) is unique in its bold approach to implement problem-based learning to all its courses in various fields – applied science, technology for the arts, engineering, sports, health and leisure, infocomm technology, hospitality, and communication. Since inception in 2002, the polytechnic in Singaporeis the only institution of higher learning to adopt the pedagogy and customised it to support learning in a One-Day One-ProblemTM framework. Students in a class of not more than 25 are presented a problem generated from daily issue likely to happen in the real scenario. A facilitator will guide the students through three meetings throughout the day and generate lively discussions and problem-solving skills. In the third meeting, students teamed up in groups of five present their findings and suggest ways to solve the problem. The facilitator will explain the ‘ideal’ solution after the students have all presented and students are encouraged to raise their opinions. Students are to submit their thoughts online in the reflection journal and the facilitator will provide feedback/response to their submission. Students are graded daily in this continuous assessment system. Four understanding tests will be conducted in one semester.
Basic Steps of PBL (continued)
l resources evaluated in group l cycle repeats until students feel the problem has been framed adequately
and all issues have been addressed l possible actions, recommendations, solutions, or hypotheses are generated l tutor groups conduct peer/selfassessments After students share and evaluate the resources they’ve gathered for the various learning issues, they decide if further information is required. If so, research continues. If not, a recommendation is formed. PBL sessions involve students in critiquing one another’s performance. Students
must comment on their own efforts and each group member’s efforts.
Facilitators and PBL
l a facilitator is key to these learning environments l models higher-order process skills l probes for student understanding l never identifies issues or states an opinion while students frame problems A facilitator models process skills, or an expert’s thinking strategies for open-ended problem solving. They might ask the students to consider, “what is it that you don’t know?” or “where can you find that information?” or “what do you think should be done next?” The facilitator does not provide clues to any of these questions, but rather, prompts students to consider “next steps” and processes along the way.
Advantages of PBL
l greater recall of knowledge, retention l interdisciplinary, can require accessing and using information from a variety of subject domains; better integration of
knowledge l development of life-long learning skills: how to research, how to communicate in groups, how to handle problems
Advantages of PBL
l increased motivation, interest in subject areas l increased student-student interaction, and student-instructor interaction