- Problem-based learning
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
Guidance is progressively faded. [adapted from Merrill (2002)]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) [http://cito.byuh.edu/merrill/text/papers/Task_Centered_Strategy.pdf Merrill, M.D. (2007) A Task-Centered Instructional Strategy. "Journal of Research on Technology in Education, 40" (1), 33-50.] ] 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 [http://www4.psychologie.uni-freiburg.de/einrichtungen/Paedagogische/cornelia/fading.html 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 problemSome 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. [http://www.cogtech.usc.edu/publications/hmelo_ep07.pdf Scaffolding and Achievement in Problem-Based and Inquiry Learning: A Response to Kirschner, Sweller, and Clark (2006)] Hmelo-Silver, Duncan, & Chinn. (2007). "Educational Psychologist, 42"(2), 99–107]
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.
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