Problem-based learning (PBL) is one of a class of instructional methods that situates learning in complex contexts. In PBL, students learn through guided experience in solving complex, open-ended problems, such as medical diagnosis or designing a playground. Developed by Howard Barrows for use in medical schools, it has expanded to other settings such as teacher education and K–12 instruction.
Problem-based learning was designed with five goals: to help students (1) construct flexible knowledge; (2) develop effective problem-solving skills;(3) develop self-directed learning skills; (4) become effective collaborators; and (5) become motivated to learn.
With its emphasis on learning through problem solving and on making key aspects of expertise visible, PBL exemplifies the cognitive apprenticeship model. In this model, knowledge is constructed by learners working on real-world problems. One key characteristic that distinguishes PBL from other cognitive apprenticeship approaches is its potential for covering an entire integrated curriculum through a well-chosen set of problems. Concepts and thinking skills are used in a variety of problems. This redundancy affords learners the opportunity to construct a deep understanding by revisiting concepts from many perspectives and by experiencing a variety of situations in which skills are applied.
The Problem-Based Learning Tutorial Process
A PBL tutorial session begins by presenting a group, typically 5 to 7 students, with a small amount of information about a complex problem. From the outset, students question the facilitator to obtain additional problem information; they may also gather facts by doing experiments or other research. At several points, students pause to reflect on the data they have collected so far and generate questions about that data and ideas about solutions. Students identify concepts they need to learn more about to solve the problem (i.e., learning issues). After considering the case with their existing knowledge, students divide up and independently research the learning issues they identified. They then regroup to share what they learned, and reconsider their ideas. When completing the task, they reflect on the problem to consider the lessons learned, as well as how they performed as self-directed learners and collaborative problem solvers.
While working, students use white boards to help guide their problem solving. The white board is divided into four columns to help them record where they have been and where they are going. The columns help remind the learners of the problem-solving process. The white board serves as a focus for group deliberations. Figure 1 shows an example of white board entries made by engineering students working on a chemical release problem. The Facts column holds information that the students obtained from the problem statement. The Ideas column serves to keep track of their evolving hypotheses about solutions, such as reducing the storage of hazardous chemicals. The students place their questions for further study into the Learning Issues column. They use the Action Plan column to keep track of plans for resolving the problem or obtaining additional information.
The Role of the Problem
Cognitive research and experience with PBL suggest that to foster learning, good problems have several
characteristics. Problems need to be complex and open ended; they must be realistic and connect with the students' experiences. Good problems require multidisciplinary solutions and provide feedback that allows students to evaluate the effectiveness of their knowledge, reasoning, and learning strategies. Problems should promote conjecture and discussion and should motivate the students' need to go out and learn. As students generate and defend their ideas, they publicly articulate their current understanding, thus enhancing knowledge construction and setting the stage for future learning.
Each problem requires a final product or performance that allows the students to demonstrate their understanding. For example, PBL has been used to help middle school students learn life science by designing artificial lungs. They conducted experiments and used a variety of other resources to learn about breathing. Their final products were models of their designs.
The Role of the Facilitator
The term facilitator refers to someone trained to facilitate student learning through PBL. In PBL facilitators are expert learners, able to model good learning and thinking strategies, rather than being content experts. The facilitator is responsible for moving students through the various stages of PBL and for monitoring the group process–ensuring that all students are involved and encouraging them to externalize their own thinking and to comment on each other's thinking. The facilitator plays an important role in modeling the thinking skills needed when self-assessing reasoning and understanding. For example, the facilitator encourages students to explain and justify their thinking as they propose solutions to problems. Their questions help model the use of hypothetical-deductive reasoning as they encourage students to tie inquiry to their hypotheses. Facilitators progressively fade their scaffolding as students become more experienced with PBL, until their questioning role is largely adopted by the students. However, they continue to actively monitor the group, making moment-to-moment decisions about how to facilitate the PBL process.
Collaborative Learning in Problem-Based Learning
Collaborative problem-solving groups are a key feature of PBL. Its small group structure helps distribute the work among the members of the group, taking advantage of individual strengths by allowing the whole group to tackle problems that would normally be too difficult for any student alone. Students often become experts in particular topics. Small group discussions and debate enhance higher-order thinking and promote shared knowledge construction.
Reflection in Problem-Based Learning
Reflection on the relation between doing and learning is needed to help the learners understand that the tasks they are doing are in the service of the questions they have asked and that these questions arise from the learning goals they have set. Thus, each task is not an end in itself but a means to achieve a self-defined learning goal.
One potential danger of PBL is that knowledge may become bound to the problem in which it is learned. Learners need to understand what principles are at play in a given task and further understand how those principles might apply to new problems. To avoid this difficulty, learners must use concepts and thinking skills in multiple problems and to reflect on their learning. Reflection is important in helping students (1) relate their new knowledge to prior understanding; (2) mindfully abstract knowledge; and (3) understand how the strategies might be applied in new situations. Problem-based learning incorporates reflection throughout the tutorial process and when completing a problem. As students make inferences that tie the general concepts and skills to the specifics of the problem that they are working on, they construct more coherent understanding. The facilitator-guided reflection helps students prepare to take what Gavriel Salomon and David Perkins, in their 1989 study, call the "high road" to transfer as they consider how their new knowledge might be useful in the future and the effectiveness of their learning and problem-solving strategies.
Empirical Support for Problem-Based Learning
Research results are converging to show that some of these goals have been successfully met. Students in problem-based curricula are more likely to use their knowledge during problem solving and to transfer higher-order thinking skills to new situations. Cindy Hmelo has studied PBL in medical students and found that when asked to provide an explanation for a patient problem, the students in problem-based curricula were more accurate in their diagnoses, more likely to apply scientific concepts, and constructed better quality explanations than students in traditional curricula. This study provides evidence that PBL students transfer their knowledge and strategies to new problems. Shelagh Gallagher and William Stepien have studied the effects of PBL on gifted high school students. In one study, they examined the effect of a PBL intervention on content knowledge in social studies and found that students in PBL learned as much content as students in traditional instruction. In another study Gallagher, Stepien, and Hilary Rosenthal, comparing students taking a PBL science and society elective with students taking other classes, found that PBL students became better at problem-finding than comparison students. Most studies of PBL have been conducted either in medical schools or in other highly selected populations such as gifted high school students, but Hmelo, Douglas Holton, and Janet Kolodner conducted a 2000 preliminary study with middle school students learning life science. The students in the PBL intervention learned more than a comparison class, but because the students were not actually able to get feedback by implementing their solution, they did not achieve as deep an understanding as the investigators had expected.
Problem-based learning was designed to help students become flexible thinkers. Although the research on PBL is promising, the effects of PBL need to be examined more widely. The challenge ahead lies in understanding how the potential of PBL can be harnessed in diverse settings. Understanding the nature of the tutorial process, including the role of the problem and facilitator, collaboration among peers, and the importance of student reflection is necessary to successfully implement PBL and to prepare students to think in the world beyond school.
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CINDY E. HMELO-SILVER
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