Problem-based learning (PBL) is a student-centered pedagogy in which students learn about a subject through the experience of problem solving. Students learn both thinking strategies and domain knowledge. The PBL format originated from the medical school of thought, and is now used in other schools of thought too. The goals of PBL are to help the students develop flexible knowledge, effective problem solving skills, self-directed learning, effective collaboration skills and intrinsic motivation. Problem-based learning is a style of active learning.
Working in groups, students identify what they already know, what they need to know, and how and where to access new information that may lead to resolution of the problem. The role of the instructor (known as the tutor in PBL) is to facilitate learning by supporting, guiding, and monitoring the learning process. The tutor must build students' confidence to take on the problem, and encourage the students, while also stretching their understanding. PBL represents a paradigm shift from traditional teaching and learning philosophy, which is more often lecture-based. The constructs for teaching PBL are very different from traditional classroom/lecture teaching.
- 1 Meaning
- 2 History
- 3 Supporters
- 4 Constructivism and PBL
- 5 Supporting evidence
- 6 Examples of PBL in curricula
- 7 Criticisms
- 8 Other outcomes
- 9 See also
- 10 References
- 11 External links
Barrows defines the Problem-Based Learning Model as:
- 1. Student Centered Learning
- 2. Learning is done in Small Student Groups, ideally 6-10 people
- 3. Facilitators or Tutors guide the students rather than teach
- 4. A Problem forms the basis for the organized focus of the group, and stimulates learning
- 5. The problem is a vehicle for the development of problem solving skills. It stimulates the cognitive process.
- 6. New knowledge is obtained through Self-Directed Learning (SDL).
In order to instill a project based learning environment into a classroom, the teacher must revolve his or her teaching style around five main criteria.
- 1. Centrality
- 2. Driving Question
- 3. Constructive Investigations
- 4. Autonomy
- 5. Realism
The first being centrality, the projects are the curriculum in this case so everything the student needs to learn should be centered around the project that he or she is working on. The second criterion that a teacher must meet is that there must be a driving question that the student must answer through completing the project. This question is the most important aspect to a successful project based learning environment because it is what motivates the student to learn as well as gives the student an idea of what knowledge is expected to be learned from the project. Also the question can not have a predetermined outcome, it should require the student to use prior knowledge to come up with a conclusion; however, the project should not be able to be put together based solely on prior knowledge. The other criteria are constructive investigations, autonomy, and realism, all of these are important for the student because it helps pull the student into the project and capture the attention as well as allows for the student to make connections to real world situations. This is more beneficial than a test because the students have to make these connections on their own and gather information that interests them instead of just memorizing facts for a test. 
PBL was pioneered in the medical school program at McMaster University in Hamilton, Ontario, Canada in the late 1960s by Howard Barrows and his colleagues. Traditional medical education disenchanted students, who perceived the vast amount of material presented in the first three years of medical school as having little relevance to the practice of medicine and clinically based medicine. The PBL curriculum was developed in order to stimulate the learners, assist the learners in seeing the relevance of learning to future roles, maintain a higher level of motivation towards learning, and to show the learners the importance of responsible, professional attitudes.
Problem-based learning has subsequently been adopted by other medical school programs, adapted for undergraduate instruction, as well as K-12. The use of PBL has expanded from its initial introduction into medical school programs to include education in the areas of other health sciences, math, law, education, economics, business, social studies, and engineering. The use of PBL, like other student-centered pedagogies, has been motivated by recognition of the failures of traditional instruction. and the emergence of deeper understandings of how people learn. Unlike traditional instruction, PBL actively engages the student in constructing knowledge. PBL includes problems that can be solved in many different ways and have more than one solution.
Advocates of PBL claim it can be used to enhance content knowledge while simultaneously fostering the development of communication, problem-solving, critical thinking, collaboration, and self-directed learning skills. PBL may position students in a simulated real world working and professional context which involves 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.
Constructivism and PBL
Problem Based Learning addresses the need to promote lifelong learning through the process of inquiry and constructivist learning. PBL can be considered a constructivist approach to instruction, emphasizing collaborative and self-directed learning and being supported by flexible teacher scaffolding. Yew and Schmidt, Schmidt, and Hung elaborate on the cognitive constructivist process of PBL:
- Learners are presented with a problem and through discussion within their group, activate their prior knowledge.
- Within their group, they develop possible theories or hypotheses to explain the problem. Together they identify learning issues to be researched. They construct a shared primary model to explain the problem at hand. Facilitators provide scaffold, which is a frame work on which students can construct knowledge relating to the problem.
- After the initial team work, students work independently in self directed study to research the identified issues.
- The students re-group to discuss their findings and refine their initial explanations based on what they learned.
PBL follows a constructivist perspective in learning as the role of the instructor is to guide and challenge the learning process rather than strictly providing knowledge. 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. PBL assists in processes of creating meaning and building personal interpretations of the world based on experiences and interactions. PBL assists to guide the student from theory to practice during their journey through solving the problem.
Several studies support the success of the constructivist problem-based and inquiry learning methods. One example is a study on a project called GenScope, an inquiry-based science software application, which found that students using the GenScope software showed significant gains over the control groups, with the largest gains shown in students from basic courses.
One large study tracked middle school students' performance on high-stakes standardized tests to evaluate the effectiveness of inquiry-based science. The study found a 14 percent improvement for the first cohort of students and a 13 percent improvement for the second cohort. The 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.
Another study from Slovenia looked at whether students who learn with PBL are better at solving problems and if their attitudes towards mathematics were improved compared to their peers in a more traditional curriculum. The study found that students who were exposed to PBL were better at solving more difficult problems, however, there was no significant difference in student attitude towards mathematics.
Examples of PBL in curricula
In Malaysia, an attempt is being made to introduce a problem-based learning model in secondary mathematics, with the aim of educating citizens to prepare them for decision-making in sustainable and responsible development. This model called problem-based learning the four core areas (PBL4C) first sprouted in SEAMEO RECSAM in 2008, and as a result of training courses conducted, a paper was presented at the EARCOME5 conference in 2010, followed by two papers during the 15th UNESCO-APEID conference in 2011. This model has since expanded in its use in the field of education management, Education for International & Intranational Understanding (EIU), and human resource management. Subsequently, many Malaysian universities began implementing PBL in their curricula in an effort to improve the quality of their education. 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). In Universiti Malaya, the Bachelor of Medicine, Bachelor of Surgery and Bachelor of Dental Surgery courses included several sessions of problem-based learning in their curriculum as a way of teaching interactions between students.
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 School of Medicine indicates that PBL has a positive effect on the students' competency as physicians after graduation.
Monash University was the second institution to adopt PBL within a medical school environment and continues to apply this within the Faculty of Medicine, Nursing and Health Sciences for the Bachelor of Medicine / Bachelor of Surgery (MBBS) programs delivered in Australia and Malaysia.
Maastricht University offers its whole program in PBL format only, as does St. George's University of London, another pioneer in the PBL format. The University of Limerick graduate entry medical school in Ireland followed by adapting the SGUL program as well as other programs to also provide its program in PBL format only. In 1983 the college of medicine and medical sciences was founded in Bahrain as part of the Arabian Gulf University. It adopts a problem-based learning curriculum from the beginning and offers its MD program in PBL only. In 1998, Western University of Health Sciences opened its College of Veterinary Medicine, with curriculum based completely on PBL.
In 2002, UC Berkeley – UCSF Joint Medical Program (JMP), an accredited five year Master of Science/Medical Doctorate Program housed at University of California, Berkeley School of Public Health, began offering a 100% case based curriculum to their students in their pre-clerkship years. The curriculum integrates the basic and preclinical sciences while fostering an understanding of the biological, social, and moral contexts of human health and disease. The students spend their last two clerkship years at University of California, San Francisco.
In 2002, Gadjah Mada University of Yogyakarta, Indonesia began offering an International Medicine program based on problem-based learning. Gazeira University in Sudan was the first in the country to adopt PBL in its medical college, a trend that was followed by some of the newer medical colleges. In 2008 the famous Faculty of Medicine of the University of Khartoum, which was following a traditional curriculum since its foundation in 1924 made a being change in curriculum structure by adopting a blend curriculum that incorporate problem solving learning strategies.
In 2008, Parramatta Marist High School a secondary Catholic school in Australia employed the methods of PBL in their teaching for year 9 and 10 boys. The learning system was a great success and since has been expanded to lower grades to challenge students to think outside of the box and relate content drive courses to problems in the real world.
North Lawndale College Prep High School (NLCP), on Chicago's west side, continues to refine its very high expectations Interdisciplinary Projects, or I-Projects. As they progress freshman through senior year, these vertically aligned projects involve increasingly rigorous Common Core State Standards in research, close reading, quantitative reasoning, argumentation, writing, and presentation skills. Each NLCP Junior and Senior Project derives itself from the student's own driving question (examples of driving questions include "How can genocide be stopped globally?" and "Does making obesity a disease help or harm obese people?"). Additionally and starting in 2014, all NLCP Senior Project Presentations will include the senior's creation of an artistic element that somehow expresses his/her argument, e.g., a documentary film, a website, a business proposal, a literary portfolio, a visual art portfolio, a unique oratory, or performative debate. Noodletools, "a powerful, integrated platform for research and literacy," is the assistive technology for North Lawndale's endeavor.
The transdisciplinary field of ecological economics has embraced problem-based learning as a core pedagogy. A workbook developed by Joshua Farley, Jon Erickson, and Herman Daly organizes the problem-solving process into (1) building the problem base, (2) analyzing the problem, (3) synthesizing the findings, and (4) communicating the results. Building the problem base includes choosing, defining, and structuring an ecological economic problem. Analysis is breaking down of a problem into understandable components. Synthesis is the re-integration of the parts in a way that helps better understand the whole. Communication is the translation of results into a form relevant to stakeholders, broadly defined as the extended peer community.
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 et al. conducted several classroom-based studies with students studying algebra problems. 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. 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 and assisting in decreasing the cognitive load on learners.
Evaluation of the effects of PBL learning in comparison to traditional instructional learning have proved to be a challenge. Various factors can influence the implementation of PBL: extent of PBL incorporation into curriculum, group dynamics, nature of problems used, facilitator influence on group, and the motivation of the learners. There are also various outcomes of PBL that can be measured including knowledge acquisition and clinical competence. Additional studies are needed to investigate all the variables and technological scaffolds, that may impact the efficacy PBL.
Demands of Implementing
- Prepare faculty for change
- Establish a new curriculum committee and working group
- Designing the new PBL curriculum and defining educational outcomes
- Seeking Advice from Experts in PBL
- Planning, Organizing and Managing
- Training PBL facilitators and defining the objectives of a facilitator
- Introducing Students to the PBL Program
- Using 3-learning to support the delivery of the PBL program
- Changing the assessment to suit the PBL curriculum
- Encouraging feedback from students and teaching staff
- Managing learning resources and facilities that support self directed learning
- Continuing evaluation and making changes (pg. 809-812)
Hung reviews the various models of PBL, Barrow's original concept or "pure PBL", the Hybrid PBL and lecture based learning with problem solving activities. In general these models form a continuum where the level of instruction and lecture are inversely proportional to the amount of self-directed learning. The individual Problem design, or "trigger" must ultimately guide students to obtain the learning objectives. Azer reviews the detailed objectives for constructing "the problem" for PBL. Facilitator selection, training and development is very important to PBL. Students respond better to motivated and enthusiastic facilitators. It is the facilitator's role to direct students during the tutorials. Guiding students learning entails much more time then simply giving students the answers. Kol et al.(2008) reported PBL facilitator-student contact time was 3-4 times greater than instructors in traditional methods.
One of the aims of PBL is the development of self-directed learning (SDL) skills. In Loyens, Magda & Rikers' discussion, SDL is defined as "a process in which individuals take the initiative…in diagnosing their learning needs, formulating goals, identifying human and material resources, choosing and implementing appropriate learning strategies, and evaluating learning outcomes." By being invited into the learning process, students are also invited to take responsibility for their learning, which leads to an increase in self-directed learning skills. In Severiens and Schmidt’s study of 305 first year college students, they found that PBL and its focus on SDL led to motivation for students to maintain study pace, led to social and academic integration, encouraged development of cognitive skills, and fostered more study progress than students in a conventional learning setting. PBL encourages learners to take a place in the academic world through inquiring and discovery that is central to problem-based learning.
PBL is also argued as a learning method that can promote the development of critical thinking skills. In PBL learning, students learn how to analyze a problem, identify relevant facts and generate hypotheses, identify necessary information/knowledge for solving the problem and make reasonable judgments about solving the problem.
Employers have appreciated the positive attributes of communication, teamwork, respect and collaboration that PBL experienced students have developed. These skills provide for better future skills preparation in the ever-changing information explosion. PBL curriculum includes building these attributes through knowledge building, written and interpersonal interactions and through the experience of the problem solving process.
- Discovery learning
- Project-based learning
- Educational psychology
- Inquiry-based learning
- Learning by teaching (LdL)
- Active learning
- McMaster University
- Collaborative learning
- Minnesota State University, Mankato Masters Degree in Experiential Education
- Observational learning
- Hmelo-Silver, Cindy E. (2004). "Problem-Based Learning: What and How Do Students Learn?". Educational Psychology Review 16 (3): 235. doi:10.1023/B:EDPR.0000034022.16470.f3.
- Schmidt, Henk G; Rotgans, Jerome I; Yew, Elaine HJ (2011). "The process of problem-based learning: What works and why". Medical Education 45 (8): 792–806. doi:10.1111/j.1365-2923.2011.04035.x. PMID 21752076.
- Hung, Woei (2011). "Theory to reality: A few issues in implementing problem-based learning". Educational Technology Research and Development 59 (4): 529. doi:10.1007/s11423-011-9198-1.
- Barrows, Howard S. (1996). "Problem-based learning in medicine and beyond: A brief overview". New Directions for Teaching and Learning 1996 (68): 3. doi:10.1002/tl.37219966804.
- Krajeik, Joseph; Phyllis C. Blummenfeld, Ronald W. Marx, and Elliot Soloway (1994). "Collaborative Model for Helping Middle Grade Science Teachers Learn Project-based Instruction.". Chicago Journals 94: 483–497.
- Neville, Alan J. (2009). "Problem-Based Learning and Medical Education Forty Years on". Medical Principles and Practice 18 (1): 1–9. doi:10.1159/000163038. PMID 19060483.
- Armstrong, Elizabeth G (2008). "A Hybrid Model of Problem-based Learning". In Boud, David; Feletti, Grahame. The challenge of problem-based learning. London: Routledge. ISBN 978-0-7494-2560-9.
- Duch, Barbara J.; Groh, Susan; Allen, Deborah E. (2001). The power of problem-based learning : a practical "how to" for teaching undergraduate courses in any discipline. (1st ed.). Sterling, VA: Stylus Pub. ISBN 1579220371. [page needed]
- Peters, José A. Amador, Libby Miles, C.B. (2006). The practice of problem-based learning : a guide to implementing PBL in the college classroom. Bolton, Mass.: Anker Pub. Co. ISBN 978-1933371078.[page needed]
- Gasser, Kenneth W. (June 2011). "Five Ideas for 21st Century Math Classrooms". American Secondary Education 39 (3): 108–16. Retrieved 16 November 2012.
- Wingspread Conference. (1994). Quality Assurance in Undergraduate Education: What the Public Expects. Denver, CO: Education Commission of the States[page needed]
- Kenney, Shirley Strum. "Reinventing Undergraduate Education:A Blueprint for America's Research Universities". The Boyer Commission on Educating Undergraduates in the Research University. Northern Illinois University. Retrieved 17 November 2012.
- How people learn brain, mind, experience, and school (Expanded ed., 4. printing ed.). Washington, DC: National Acad. Press. 2001. ISBN 978-0309070362.[page needed]
- Cotič, Mara; Zuljan, Milena Valenčič (2009). "Problem‐based instruction in mathematics and its impact on the cognitive results of the students and on affective‐motivational aspects". Educational Studies 35 (3): 297. doi:10.1080/03055690802648085.
- Barrett, Terry (2010). "The problem‐based learning process as finding and being in flow". Innovations in Education and Teaching International 47 (2): 165. doi:10.1080/14703291003718901.
- Wells, Samantha H; Warelow, Philip J; Jackson, Karen L (2009). "Problem based learning (PBL): A conundrum". Contemporary Nurse 33 (2): 191–201. doi:10.5172/conu.2009.33.2.191. PMID 19929163.
- Schmidt, Henk G.; Loyens, Sofie M. M.; Van Gog, Tamara; Paas, Fred (2007). "Problem-Based LearningisCompatible with Human Cognitive Architecture: Commentary on Kirschner, Sweller, and Clark (2006)". Educational Psychologist 42 (2): 91–7. doi:10.1080/00461520701263350.
- Yew, Elaine H. J.; Schmidt, Henk G. (2011). "What students learn in problem-based learning: A process analysis". Instructional Science 40 (2): 371–95. doi:10.1007/s11251-011-9181-6.
- Hmelo-Silver, Cindy E.; Barrows, Howard S. (2006). "Goals and Strategies of a Problem-based Learning Facilitator". Interdisciplinary Journal of Problem-based Learning 1. doi:10.7771/1541-5015.1004.
- Dolmans, Diana H J M; De Grave, Willem; Wolfhagen, Ineke H A P; Van Der Vleuten, Cees P M (2005). "Problem-based learning: Future challenges for educational practice and research". Medical Education 39 (7): 732–41. doi:10.1111/j.1365-2929.2005.02205.x. PMID 15960794.
- Hmelo, C.E.; Evensen, D.H. (2000). "Problem-based learning: Gaining insights on learning interactions through multiple methods of inquiry". In Evensen, Dorothy H.; Hmelo, Cindy E.; Hmelo-Silver, Cindy E. Problem-Based Learning: A Research perspective on learning interactions. pp. 1–18. ISBN 978-0-8058-2644-9.
- Edens, Kellah M. (2000). "Preparing Problem Solvers for the 21st Century through Problem-Based Learning". College Teaching 48 (2): 55–60. doi:10.1080/87567550009595813. JSTOR 27558988.
- Hmelo-Silver, Cindy E.; Duncan, Ravit Golan; Chinn, Clark A. (2007). "Scaffolding and Achievement in Problem-Based and Inquiry Learning: A Response to Kirschner, Sweller, and Clark (2006)". Educational Psychologist 42 (2): 99. doi:10.1080/00461520701263368.
- Koh, G. C.-H.; Khoo, H. E.; Wong, M. L.; Koh, D. (2008). "The effects of problem-based learning during medical school on physician competency: A systematic review". Canadian Medical Association Journal 178 (1): 34–41. doi:10.1503/cmaj.070565. PMC 2151117. PMID 18166729.
- Teoh, B.T.; Preechaporn, W., & Leong, C. K. "Problem-based learning in the 4 Core Areas (PBL4C) in the search of excellence in mathematics instruction". Paper presented at 5th EARCOME Conference. Retrieved 17 November 2012.
- "Problem-Based Learning Curriculum A Success For Medical School". Medicalnewstoday.com. Retrieved 2012-11-16.
- Schmidt, PL; Trevejo, RT; Tkalcic, S (2008). "Veterinary public health in a problem-based learning curriculum at the Western University of Health Sciences". Journal of veterinary medical education 35 (2): 212–8. doi:10.3138/jvme.35.2.212. PMID 18723806.
- "UC Berkeley School of Public Health". Retrieved 2014-01-29.
- "Nugrahan - Our Partners - Gadjah Mada". Medialux.com.my. Retrieved 2012-11-16.
- "Problem-based learning at the Libyan International Medical University". limu.edu.ly. 2009. Retrieved 2012-02-18.
- Farley, Joshua; Erickson, Jon D.; Daly, Herman (2005). Ecological Economics: a Workbook for Problem-Based Learning. Washington, DC: Island Press.[page needed]
- Sweller, John (2006). "The worked example effect and human cognition". Learning and Instruction 16 (2): 165. doi:10.1016/j.learninstruc.2006.02.005.
- Sweller, J (1988). "Cognitive load during problem solving: Effects on learning". Cognitive Science 12 (2): 257. doi:10.1016/0364-0213(88)90023-7.
- Sweller, John; Van Merrienboer, Jeroen J. G.; Paas, Fred G. W. C. (1998). Educational Psychology Review 10 (3): 251. doi:10.1023/A:1022193728205.
- Schmidt, H. G. and Moust, JHC (2000). Problem-based learning : a research perspective on learning interactions. Hillsdale, N.J.: L. Erlbaum. pp. 19–51. ISBN 978-0805826456.
- Henry, Holly R.; Tawfik, Andrew A.; Jonassen, David H.; Winholtz, Robert A.; Khanna, Sanjeev (2012). ""I Know This is Supposed to be More Like the Real World, but . . .": Student Perceptions of a PBL Implementation in an Undergraduate Materials Science Course". Interdisciplinary Journal of Problem-based Learning 6. doi:10.7771/1541-5015.1312.
- Azer, Samy A. (2011). "Introducing a problem-based learning program: 12 tips for success". Medical Teacher 33 (10): 808–13. doi:10.3109/0142159X.2011.558137. PMID 21942480.
- McLean, Michelle; Van Wyk, Jacqueline Van (2006). "Twelve tips for recruiting and retaining facilitators in a problem-based learning programme". Medical Teacher 28 (8): 675–9. doi:10.1080/01421590601110033. PMID 17594576.
- Loyens, Sofie M. M.; Magda, Joshua; Rikers, Remy M. J. P. (2008). "Self-Directed Learning in Problem-Based Learning and its Relationships with Self-Regulated Learning". Educational Psychology Review 20 (4): 411. doi:10.1007/s10648-008-9082-7.
- Severiens, Sabine E.; Schmidt, Henk G. (2008). "Academic and social integration and study progress in problem based learning". Higher Education 58: 59. doi:10.1007/s10734-008-9181-x.
- Şendağ, Serkan; Ferhan Odabaşı, H. (2009). "Effects of an online problem based learning course on content knowledge acquisition and critical thinking skills". Computers & Education 53: 132. doi:10.1016/j.compedu.2009.01.008.
- Vardi, Iris; Ciccarelli, Marina (2008). "Overcoming problems in problem‐based learning: A trial of strategies in an undergraduate unit". Innovations in Education and Teaching International 45 (4): 345. doi:10.1080/14703290802377190.
- Barr, Robert B.; Tagg, John (1995). "From TeachingtoLearning —A New Paradigm for Undergraduate Education". Change: the Magazine of Higher Learning 27 (6): 12. doi:10.1080/00091383.1995.10544672.
- Kirschner, Paul A.; Sweller, John; Clark, Richard E. (2006). "Why Minimal Guidance During Instruction Does Not Work: An Analysis of the Failure of Constructivist, Discovery, Problem-Based, Experiential, and Inquiry-Based Teaching". Educational Psychologist 41 (2): 75. doi:10.1207/s15326985ep4102_1.
- Merrill, M. David (2002). "A pebble-in-the-pond model for instructional design". Performance Improvement 41 (7): 41. doi:10.1002/pfi.4140410709.
- Schmidt, H. G. (1993). "Foundations of problem-based learning: Some explanatory notes". Medical Education 27 (5): 422–32. doi:10.1111/j.1365-2923.1993.tb00296.x. PMID 8208146.
- Schmidt, H. G. (1983). "Problem-based learning: Rationale and description". Medical Education 17 (1): 11–6. doi:10.1111/j.1365-2923.1983.tb01086.x. PMID 6823214.