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Problem-based learning: undergraduate physics byresearchDerek Raine a & Sarah Symons ba Department of Physics and Astronomy & Centre for Interdisciplinary Science , University ofLeicester , Leicester , UKb IntegratedScience, Department of Physics and Astronomy , McMaster University ,Hamilton , CanadaPublished online: 16 Dec 2011.

To cite this article: Derek Raine & Sarah Symons (2012) Problem-based learning: undergraduate physics by research,Contemporary Physics, 53:1, 39-51, DOI: 10.1080/00107514.2011.615162

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Problem-based learning: undergraduate physics by research

Derek Rainea* and Sarah Symonsb

aDepartment of Physics and Astronomy & Centre for Interdisciplinary Science, University of Leicester, Leicester, UK;bIntegrated Science, Department of Physics and Astronomy, McMaster University, Hamilton, Canada

(Received 28 April 2011; final version received 15 August 2011)

Problem-based learning (PBL) is an established pedagogy in many areas of education for the professions. Althoughthere is an awareness of PBL in many departments of physics in the UK and many claim to include PBL-likeinstruction to some degree, it has made rather less impact in the physical sciences. This paper describes the aims ofPBL and how these are implemented based on our experiences in Physics at the University of Leicester. It is not ourpurpose to discuss here the parochial details of this programme which are partly historical and adapted to localconditions. (The interested reader can find them on our web site.) Rather we look at general aspects of PBL inPhysics in the light of our experience and that of others. In addition to numerous examples of PBL problems, ourdiscussion includes the educational and philosophical underpinnings of PBL, the nature of the ‘problem’ in PBL,issues in facilitation and assessment as well as a brief review of the published evaluations of PBL. Space constraintsmean we do not discuss the process of change management.

Keywords: problem-based; pedagogy; student-centred

1. Introduction

I think, however, that there isn’t any solution to thisproblem of education other than to realize that the bestteaching can be done only when there is a directindividual relationship between a student and a goodteacher—a situation in which the student discusses theideas, thinks about the things, and talks about thethings. It’s impossible to learn very much by simplysitting in a lecture, or even by simply doing problemsthat are assigned. But in our modern times we have somany students to teach that we have to try to find somesubstitute for the ideal. [1]

So says Feynman in the introduction to his Six EasyPieces. It is well known that the original FeynmanLectures were not a complete success for the targetaudience of freshmen physicists.

Walter Lewin’s lectures are available on the web.To quote from the blog ‘Pseudoteaching’:1 ‘Hisdemonstrations were thrilling. His board work wasimpeccable . . . . It looks like good teaching, but he wasthe one doing all the talking. It looks like the studentsare learning, but they were just sitting there watching.’To judge by the failure and drop-out rates, andconsidering that traditional teaching does not getmuch better, it did not work that well. As a resultMIT has abandoned lectures for introductory physicscourses and replaced them with small group interactiveinstruction.

In contrast to undergraduate students in largeclasses, students who survive to postgraduate researchget Feynman’s ideal education. How can the benefits ofthis research approach be extended to the under-graduate curriculum? This paper is about our experi-ence at the University of Leicester in addressing sucha scaling through problem-based learning (PBL)2 [2].The paper is organised as follows: in this section weillustrate PBL in physics through an example. Section 2provides a very brief history of PBL and discusses therelationship with educational theory. This will providesome insight into the motivation for introducing PBL.For readers who are more interested in aspects ofimplementation, Section 3 deals with the character-istics of PBL illustrated by a further selection of PBLproblems based on our experience. Section 4 deals withclass-room teaching and Section 5 with assessment.Finally we give a brief review of some of the resultsfrom evaluations of the effectiveness of PBL.

There are many ways of defining PBL [3]; here isone: problem-based learning is ‘a student-centredmethod of teaching in which students learn byinvestigating real-world problems and, working ingroups, seek out the tools necessary to solve them’.3

Let us illustrate what this might mean for Physicsthrough an example. Figure 1, part (a) shows a set ofstandard exercises on AC theory as might be set at theend of a lecture. Figure 1, part (b) shows a problem

*Corresponding author. Email: jdr@le.ac.uk

Contemporary Physics

Vol. 53, No. 1, January–February 2012, 39–51

ISSN 0010-7514 print/ISSN 1366-5812 online

� 2012 Taylor & Francis

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(somewhat abbreviated) covering a similar set oflearning objectives as it might be set at the start of aPBL class. The traditional approach starts with ananswer and ends with a question; the PBL approachuses the question to drive the student learning.

As we implement this at Leicester, the PBL activityoccupies four three-hour laboratory sessions over threeweeks running alongside three lectures on AC theory.The activity is supported by directed readingfrom prepared notes and the course text book andthree group problem-solving workshops (or ‘exerciseclasses’)4. Two of the laboratory sessions are precededby short introductions which provide some stagingpoints.

Some points to note: we have not abolished lecturesor exercise classes; rather the problem provides acontext in which the lectures and classes becomemeaningful. Under the guidance of a ‘research super-visor’ students explore the material required for thesolution of the problem. Furthermore, the problem isfar from being a pattern-matching exercise based onthe lecture material. The problem in fact is ill-posedand open-ended: various answers are possible depend-ing on the accuracy with which one can determine theresonant frequency and hence deduce the particle sizefrom the dielectric constant. On the other hand,students who get at least as far as constructing aworking circuit, and explaining it well, will probably

have achieved the core learning objectives. Theproblem has its flaws: (i) it is slightly artificial in thatit might be easier in practice to measure the DCcapacitance (although there is nothing to stop studentscoming to this conclusion) and (ii) coupling a signalgenerator and loudspeaker to the circuit adds someextraneous complications. The problem also under-went several iterations in terms of the problemstatement, the expectations of how much studentscould achieve, the level of instructional supportrequired, and the scheduling needed to leave adequatetime for reflection between sessions. This last point ismore important than the length of the PBL problems:they can range from an hour to a semester, providedthat hard-working students have sufficient time tothink about what they are doing.

Analysing somewhat more closely the anatomy of aPBL problem we find the following.

The problem brief comprises text and objects givento students at the beginning of a problem whichcontains within it, either explicitly or implicitly, the‘problem’ (issue, dilemma, or puzzle) which thestudents should explore. The problem brief includesan appropriate combination of hook, trigger, andscenario materials. Some implementations of PBLexclude an explicit statement of the problem, believingthat the first action the students should undertakeshould be the identification of a problem. In other

Figure 1. Example problem (a): the student is asked to consider the properties of an LCR circuit in (a) a traditional end-of-chapter exercise and (b) a PBL problem.

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models, more guidance is given about the directionthat groups should take.

A hook is an object which engages students in thecontext of the problem. It might be a newspaper storywith a provocative headline, an intriguing image, or apoem (not an example we have made use of yet) and soon. Often, the hook does not contain the problem itselfor clues to directions to take within a problem. Theseare added in the trigger.

A trigger is an object (usually text) which containsindications of how to attack the problem by suggestingpossible lines of enquiry or research methods. Thetrigger in our example problem (b) (Figure 2) isthe final comment in the text that clearly defines therequired response.

A scenario sets the context for the problem. Often,it tells the students what role or stance they shouldtake when solving the problem; for example: you area group of research chemists, or: you are an environ-mental pressure group.

In the example of Figure 1 the hook is theinstruction from the research department, the briefis the statement of the problem. The trigger (notreproduced here) would be the instructions for theinvestigation and report. Figure 2 shows anotherexample of a PBL problem.5

2. A brief history of PBL

Although there are other claims to priority, PBL as aninstitutionalised form of tuition is generally said tohave originated in the McMaster medical school [4]as a response to evidence of the ineffectiveness of thethen current medical education in training doctors tobe doctors and not professional students. The keyelements of the McMaster model are self-directed,self-assessed learning based on a set of carefully crafted

real-world problems that take students a step at a timethrough their medical training. Students meet inrelatively large groups of 8 to 12 with a dedicatedfacilitator. The concept was embraced in the medicalschools at Newcastle (New South Wales) and Maas-tricht, which collaborated to some extent on thedevelopment of their programmes [5]. From therethe methodology spread to professional educationmore generally, for example in other medically relatedprofessions (nursing and midwifery), architecture, lawand engineering. In the humanities, PBL has beenemployed in sociology and related disciplines, particu-larly anthropology. The uptake in the sciences has beenslower, although some chemistry courses have sig-nificant elements of PBL and the approach has beenembraced in physics in a handful of institutions.

PBL can be found blended in various ways withmore traditional pedagogy and the form of facilitationand other support also differs widely. One thing thatPBL definitely is not however, although this is some-times confused, is learning through ‘problem solving’where the problems are set as tests and for practiceafter the relevant material has been delivered. In all ofthe variations of PBL the key feature is that theproblem should come first: ‘The principal idea behindPBL is that the starting point for learning should be aproblem, a query, or a puzzle that the learner wishes tosolve.’ [6]. (This is obvious in postgraduate work: as faras we know, no physics researcher attempts to masterthe complete contents of each volume of PhysicalReviews just in case there might be something usefulfor the future.6) The spread of PBL has also seen localadaptations of the PBL method and a broadening ofthe approach to a number of ‘xBLs’, notably projectbased learning, research-based learning, context-basedlearning, case-based learning and enquiry-based learn-ing, wherein the initial stimuli are extended fromproblem scenarios to more general research questionsand cases. Even the requirement for group work hasbeen questioned.

Parallel to the development of PBL as a pedagogyhas been the contribution of educational research toour understanding of how we learn. There was a timewhen there was a widespread opinion that, sincebehaviour is the only observable, learning is relatedto behavioural change. This implies repetition andreward for actions that are measurable. This approachis at best relevant to the acquisition of technical skills.However, dissatisfaction with the narrow confines ofbehaviourism, and an increasing acceptance of mentalstates as meaningful descriptions, led to increasinginterest in how knowledge is acquired, that is, theoriesof cognition. In the context of physics, many experi-ments have shown how students can be trained to givethe right answers in a physics lesson but revert to an

Figure 2. Example problem (b): the hook and trigger (seetext) for a problem on the Doppler shift. Some scenarios forthis problem, as suggested by academic staff in a trainingworkshop for PBL, are: in a law class, to introduce mobilephone technology, for the biology of hearing and, of course,for the basic physics of the Doppler shift.

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Aristotelian world view outside their classes (e.g. [7]).We therefore have to think about how we learn, that is,cognitive theories of learning.

One important aspect of cognitive theories oflearning was the stress on the acquisition of newknowledge as an extension of what is already known.The most widely known of these theories are Piaget’sstages of development [8] and Vygotsky’s zone ofproximal development [9]. In as far as it is relevant tohigher education, Piaget’s important insight is intoassimilation and accommodation: the way we fit newknowledge into our existing structures and the way wechange our structures to accommodate new informa-tion.7 The manner in which this is related to the socialcontext was emphasised primarily by Vygotsky8 andleads to social constructivist theories, according towhich we individually construct knowledge. These areanathema to many physical scientists who think thatscientific knowledge is objective: perhaps it is, but whatwe make of it and the way we understand it as we learnis not, as we shall see.

How does information acquire a meaning? Thereare two requirements: prior knowledge and context.Figure 3 shows an example of the way in whichknowledge has to be constructed from the words andsymbols. (There is nothing special about physics here:road signs are probably largely meaningless to some-one who has never seen a motor vehicle.) We make thisconstruction in a social context, building on what wealready know. ‘ . . . careful inspection of methods whichare permanently successful in formal education . . . willreveal that they depend for their efficiency upon thefact that they go back to the type of situation whichcauses reflection out of school in ordinary life. Theygive pupils something to do, not something to learn;and if the doing is of such a nature as to demand

thinking, or the intentional noting of connections;learning naturally results’ [10].

A key element has come to be known asconstructive alignment [11]. The subject knowledgeand skills in the curriculum should be consistent withthe students’ prior knowledge and goals, assessmentshould be aligned with the teaching and there shouldbe a coherent sense of community. In traditionalteaching there is often a disjunction between theacademic physicist who believes himself to be teachingphysics and the student who is learning to passexaminations, between the fragmented prior knowl-edge of the student and the assumptions about whathas already been covered by the teacher and alsobetween their goals: on the one side to train aprofessional researcher, on the other, ‘anything but’.Assessment is the end-point for the teacher and thestarting point for the student, and there is often littlesense of community. By focusing on the student as aprofessional physicist manque in a research community,PBL seeks to align these elements. The students becomeresponsible for defining their own learning needsdepending on their prior knowledge and aspirations.The alignment of assessment is addressed in Section 5.

3. Characteristics of PBL in physics

PBL is characterised by a correlation with professionalpractice, large and open-ended problems and multipleinteractions including exchanges of ideas with peers.Here we consider the impact on the nature of a PBLproblem in physics, noting some objections that arisein the context of physics with some examples of howthese can be addressed.

3.1. A PBL problem encourages ‘professional’ workinghabits

The professional aspect of PBL is for us one of its mainstrengths and difficulties. The PBL approach attemptsto create successful practitioners, not merely studentssuccessfully trained to pass examinations. In disci-plines allied to professional practice, this is relativelyeasy. In medicine there is a plentiful supply of medicalhistories of increasing complexity which cannot be‘googled’ and which can therefore be used as ‘pro-blems’; in engineering likewise one can create problemsof graded difficulty while remaining true to what apractising engineer might be expected to do. In physicsprofessional practice includes – indeed mainly revolvesround – the physics laboratory. But the real intellectualchallenges faced by practising physicists are toocomplex to be used as vehicles for teaching: hencethe relegation of project work to the final year, oncethe student has ‘learnt all the basics’.

Figure 3. The figure encapsulates a lecture and an exerciseon the lecture. The equations in the figure are genuineequations from physics, but in an unfamiliar notation. Sinceany notation will be unfamiliar to the students this givessome impression of how the lecture might appear to them.The exercise is a genuine example (using the same code) thatcan be solved on the basis of the lecture. The problem is thatit can be solved by anyone with a modicum of patience quiteindependently of any understanding of the lecture, just bypattern matching. Mildly industrious students thereforereceive full marks. How are they supposed to know thatthey have not done exactly what was asked of them?

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It is very easy for students to tackle problems asamateurs, being satisfied with the first half-relevantthought as the solution. We have found ourselvesinadvertently encouraging this by setting problems incontexts where one would not expect to behave as aprofessional researcher. (For example, no-one ‘aban-doned on a desert island’ makes it a priority to keep alaboratory notebook. One is also unlikely to have afacilitator on the island.) To repeat, the professionalcontext for physics is a research team and we havefound it best that the problems keep it so. Figure 4presents a case study in which the scenario neededrescuing. The case studies in this and subsequentfigures are fictionalised versions of the truth. We runthis first year problem with the same structure asexample (a).

3.2. PBL problems are open-ended and/or multi-pathed and encourage debate

Our next desirable property for a problem, open-endedness, presents another issue. Most physicsproblems, as we currently teach the subject, are closed,in that the answer is either right or wrong. Educatorswho do not have any experience of physics havelatched on to the supposed fact that, while there may

be only one answer, there is more than one solution,that is, that problems can be tackled in a variety ofways. In our whole undergraduate careers we think wecame up with solutions to exercises that were genuinelydifferent from that expected, and not just a super-ficially different presentation of the same solution, onat most two occasions. We do not think there is muchmileage in requiring that PBL problems in the puresciences should have multiple methods of solution,although there are some possibilities in experimentaldesign work. Our approach is to require the problemcontext to be such that the answer has consequences,for example where the range of outcomes usingdifferent values for unknown quantities might affecta decision. As an illustration, a rough estimate of theability of the UK national grid to support thereplacement of petrol with electric vehicles gives avery ‘debatable’ answer. Open-endedness is alsorelevant to the obvious constraint that it should notbe possible to find a complete answer to a problem onthe internet. Figure 5 gives an example of a problemwhere the experimental accuracy attained is liable toaffect the conclusion. Figure 6 provides a case studyof an approach to genuinely open-ended problems.

3.3. A PBL problem poses a stimulating question

In strict implementations of PBL a problem shouldpose a question, not a mission statement or aninstruction to do something, as one might find in aproject. This is relatively easy when there is no pre-defined curriculum, and increasingly difficult the moreone needs to ‘cover’ material. In the light of thisdifficulty a number of variants of PBL have arisen(the xBLs), and some purists now distinguish PPBL(for pure PBL). In all cases the problem should berelevant, not just appended to a set of learningobjectives in such a way that it can be safely ignored

Figure 4. Example problem (c): a fictionalised case studyshowing how different problem statements can be builtaround the same learning objectives (some more successfullythan others). The problem incorporates elements of thedesign of laboratory experiments, the relating of theory topractical, simple computations and the mixing of differentareas of physics (electricity and fluids). This really is a real-world problem. The data in the (fuller) newspaper reportgives some indication of the wind speeds involved. Thelaboratory models will not have speeds this large so it isnecessary to understand at least some of the theory in orderto scale them up. It is not sufficient simply to get the deviceworking in the laboratory.

Figure 5. Example problem (d): Year 2 students, workingin groups of four, have four three-hour laboratory sessions tocomplete the experiments and write a computer program toanalyse the data. The reflection from a granular surface doesnot show the text book Brewster angle or the Fresnelreflection coefficients!

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[12,13]. Having accepted the possibility of a PBLapproach to classical mechanics, the PBL sceptic willpoint to quantum theory and relativity as subjectsimpossible to teach by PBL. Figure 7 is a case studyof a problem we have used to teach general relativity.

3.4. PBL problems are based in a realistic context

PBL began as pedagogy for education in the profes-sions. Professional practice provides problems ofvarying difficulty that can form the basis of astructured curriculum, even if some doctoring of theraw problems is required. In the pure sciences it seemsto be more difficult. A PBL student might be expectedto look up, say, Newton’s Laws, something that nopractising physicist would do. Nevertheless, the skillsthat a student will employ in coming to grips witha problem involving classical mechanics are thesame collection of research skills that a professionalresearcher will employ on more advanced material.

These skills extend beyond solving problems withknown closed answers. In addition, once we expandour horizon beyond the pure discipline, we can findmany questions in environmental science, biophysics,geology and so on that provide problems in physics atall levels. In the last analysis, it may be that one acceptsthat a realistic context does not mean an actualcontext. For example, many of the PBL experimentsat Leicester use simple equipment that comes upagainst the signal-to-noise problem of real life. Wecould have engineered precision equipment that wouldget round this, but we prefer to simulate the researchenvironment where the answer depends on somerealistic error analysis (Figure 8).

3.5. PBL problems encompass new areas of knowledge

Many academic staff think that they get the point ofPBL as an aid to reinforcement or revision. But ‘theycan’t solve that because we haven’t taught them thisyet’ is a common complaint about other uses of PBL.Actually, PBL is a great aid to reinforcement, even

Figure 6. Example problem (e): The Journal of SpecialTopics (JST) is an electronic journal using professionaljournal software on the department web server. Only anabbreviated version of the problem is given here, togetherwith the start of an example student response to a differentproblem. JST volume 9 is published in hard copy at http://www.lulu.com/product/paperback/journal-of-special-topics-%28vol-9%29/16131580. The associated module is largelyopen ended with multiple hooks, loosely defined objectivesand minimal academic supervision.

Figure 7. Example problem (f): relativity by PBL. Theproblem is run with two groups of four Year 3 students oversix weeks (a joint one hour session per week). A technicalreport is expected to give details of the basis for relativity(special and general) – the text suggests applications to theGPS technology as a good example as well as (or instead of)the classical tests. Symbolic manipulation programs can beused to solve Einstein’s equations and equations of motion.Black hole solutions should be investigated to be ruled out aswormholes. Some Maple code for tensor analysis is provided.Students would be expected to come to this module with abackground in vector analysis and probably some knowledgeof Cartesian tensors and special relativity. Note that thequestion is open-ended because we do not know whetherwormholes could exist!

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though this is not the main motivation. It is also truethat there is only so much new knowledge that can beincorporated in a single problem. But there shouldbe something that students decide they need to learn.This will be the thing they remember later.

3.6. A PBL problem gives students a role or point ofview

Giving a point of view is important and difficult.Students are not experts, so problems that attempt toprovide a role and a point of view by starting ‘you are anexpert in climate change . . . .’ are confusing. Construct-ing the learning issues becomes a tortuous navigation ofthe response that ‘if we were experts we would knowthat’. Often the source of the difficulty is the problem(Figure 9). Students are unlikely to be researching basicgeology if they ‘work for an oil exploration company’ butthey might be if they are doing some archaeologicalresearch. For the most part we find that most academicstaff (and students) are more comfortable if we dispensewith the pseudo roles and just treat students as ‘fellowprofessionals’, essentially as a research team with a ‘linemanager’. The point of view should be implicit in theproblem. If the problem really is to measure the speed oflight, there had better be a reason why we should not justlook it up.

3.7. A PBL problem should be engaging

This is again where a lot of the effort in constructing aPBL programme comes in. We find that students arereadily engaged by what they can easily already do, butthis defeats the object. (If they can readily do itanyway, what are they learning?) On the other hand,if it is too difficult it is not engaging, (at least, notbeyond the initial encounter with the prospect of,say, computing trajectories through gravitationalwormholes.) An engaging problem is one that it

ought to be possible for students to solve with justthe right amount of effort allowed for in the schedule(Figure 10). An engaging problem should also be oneappropriate to group work. Two obvious sources offailure are problems which neglect to recogniseresource limitations, so end up being done by a sub-group, or which clearly lend themselves to horizontaldivision. (Each group member learns the statement ofone of Newton’s laws.)

4. Facilitation

It used to be thought that there are different styles oflearning: Kolb’s divergent-convergent distinction [15]has passed into folklore and the visual, auditory andkinaesthetic (VAK or VARK) classification is anotherwell-known one [16]. In fact, each student learnsthrough multiple inputs and multiple interactions, forexample reading, writing, drawing, speaking, listening,reciting, making and measuring. PBL attempts toprovide multiple opportunities for transforming in-formation in multiple interactions with academicsubject experts, facilitators and peers. This should beviewed as building an academic community analogousto the postgraduate research community.

Figure 8. Example problem (g): this is a first year PBL runin the same way as the examples in Figures 1 and 4. Theexperiments are carried out alongside the lectures on optics.

Figure 9. Example problem (h): an example of a problem,taken from our Interdisciplinary Science degree programme,in which students are given different viewpoints This is auseful approach with large subjects, where students are notexpected to master the whole content in detail, but wheregeneral awareness is important. A more purely physics basedexample is a design task, for example of a space mission. Theproblem statement presumes that students will have tobecome experts to report to the panel. Stakeholderpositions might be chosen from the following list: OilIndustry, Car Industry, Heavy industry: mining, HeavyIndustry: manufacturing, Heavy Industry: chemicalrefineries, Environmental groups, Scientific advisory panel(e.g. National Academy of Sciences), Climate change skeptic(scientist), Solar energy sources, Wind energy sources, Hydroenergy sources, Biofuel energy sources, Developing countries:Sub-Saharan Africa, Developing countries: China/India,United Nations, Nuclear power industry, Coal/gas powerindustry, Aid/ disaster relief agencies.

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In our experience the most important and difficultaspect of building a community in PBL is facilitation[17,18]. One way to approach this is through theanalogue of the interaction between research studentand supervisor. The meeting is neither a lecture nor atutorial; although it is not a meeting of equals, itinvolves dialogue and respect for the student’s ideas.However, in PBL, the discussion is not between thefacilitator and the group, but within the group. Therole of the facilitator is to enable and promote thisdiscussion and to steer it when necessary. In the‘medical model’ of PBL the group will have a fixedfacilitator who meets their group on a regular basis.The analogue is the group research project, whichmany Physics Departments run. An alternative to thefixed facilitator is the floating facilitator who movesfrom group to group in a single or connected space andintervenes where necessary.

To enable this process to be scalable, most if not allimplementations of PBL provide what is referred to as‘scaffolding’. This supplies a structure for the students;in our implementation it can also offer somethingapproaching a script for the facilitator.

A PBL programme, like any other method ofcurriculum delivery, is based around an understandingof the way in which students learn. There are a varietyof ways in which the learning process can be described

in terms of a learning cycle. One of the best known isdue to Kolb [15] and its variants: concrete experiencegives rise to reflection, then abstraction or theformation of concepts followed by action and henceconcrete experience. The abstraction from eventsconstitutes the theoretical axis of learning, whilereflection (observation and feeling) and action formthe affective axis. We turn this from theory to practicewhen we establish a teaching schedule that supportsthis cycle (which we are free to start at any point).Figure 11 shows a simplified version of the learningcycle specific to PBL.

The distinctive feature of PBL is that it starts with aproblem. The variants of PBL that we have noted takeadvantage of some of the other positive features ofPBL, but use different starting points. In all cases thestarting point generates a set of learning issues: thingsthat need to be found out in relation to the problem.Part of the design of a PBL programme involves thedegree to which these are wholly generated by thestudent or tutor led. For example, Woods describes aChemical Engineering module in which the studentshave access to the learning objectives specified bythe tutor, to which they can compare their own only ifthey wish [2]. Where the learning issues are studentled, the tutor will normally give some guidance onpriorities or focus. The agreed learning issues form thebasis for individual research which can then be broughtto bear on the problem at the evaluation stage.

Figure 10. Example problem (i): another first year problemwhich allows students from various backgrounds toapproach the application of the laws of motion at differentlevels of sophistication and can therefore engage a range ofstudents. The notes in the figure (not given to the studentsdirectly) suggest four approaches. The problem is announcedat the beginning of the first year dynamics course and tackledtowards the end of the course with the same structure asExample (a).

Figure 11. The Problem (grounded in experience) – TheIssues (reflection, divergence) – Research (hypothesis,conceptualisation, generalisation of the problem) –Evaluation (application to the problem, convergence).

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The cycle is then repeated in the light of the newknowledge.

Figure 12 shows how this cycle can be supported byspecific stages or steps [19] that structure the studentactivity. (Other structures are available.)

One of the aims of facilitation is to build a sense ofcommunity (Figure 13). We can break this down intothree relationships: intra-group relations, inter-grouprelations and staff–student relations. As part of thefirst we need to consider the balance between groupwork and individual work.

Only individuals have learning outcomes. Thisconflicts with the division of labour that group workseems to promote. If a problem breaks down into neatchunks there is a danger that it will get divided up andshared in a manner that does not allow all students toachieve all of the learning objectives. If a problem ishighly integrated there is a danger that only a subsetof the group contribute. This is one reason why PBLdevelopers promote problems that are complex andopen-ended. One role of the facilitator is to guidestudents to plan their work so that everyone in thegroup covers the basic learning objectives. This shouldbe necessary for them to play a full role in thediscussion of the problem. The investigation phase iscarried out individually (experiment and reflect).

The main function of the group is peer tutoring,and this has two aspects. First, by discussing researchrelevant to the problem (divergence) students reinforcetheir basic knowledge. They have to speak compre-hensibly and listen critically. Second, they constructthe group response to the problem, which entails usingtheir knowledge critically (convergence).

The facilitator is key to promoting both of theseaspects. This cannot be done if the facilitator providesa lecture that effectively damps out any group

conversation, or if the facilitator allows groups towander some distance from the point or to be satisfiedwith a shallow or wrong analysis. Facilitation istherefore a delicate balance between dominating withtoo much information and being unhelpful with toolittle. We have found that, despite some of the receivedwisdom, generally it is best if the facilitator is an expertin the subject and the problem and is able to make thesejudgments (see also [20,21]). It is sometimes thoughtthat PBL curricula do away with lectures. This is notnecessarily the case. It is often crucial to provide anexpert lecture on a topic once students understand whyit is relevant.

In some implementations of PBL, groups writethemselves a set of rules and members take certainroles (which generally rotate from meeting to meeting).Rules will encompass whatever the group thinks isrequired to function effectively. In some of ourimplementations attendance rules, for example, arereinforced by penalties on marks for assessed groupwork. Groups may also assign roles for meetings, suchas chairperson and minute taker. We do not generallyimpose roles, but someone in the group has to beresponsible for making a note of who has agreed to dowhat; and then whether they have done it or not.

The final interaction is via assessment. Thisinteraction should be authentic in the context of theproblem. We shall discuss this further in the nextsection.

Finally, although it is the aspect that probablyrequires settling first, is the method of group forma-tion. This varies between implementations and evenwithin implementations as everyone has their favourite(and their least favourite, which they will be certainnever works). We have found friendship groups (wherestudents form their own groups) to be less effectivewhere group meetings occur mainly in facilitatedscheduled slots, but quite effective where groups areexpected to arrange the majority of their ownunsupervised meetings. Others will disagree. We donot like groups with too large an ability range withinthe group, which we find benefits no-one, so weengineer groups to this extent. Some of our groupstend to be long lasting, some vary from module tomodule, largely depending on the density of PBLwithin the programme.

5. Assessment

A lot of the issues in PBL arise because of assessment.Assessment is expensive on staff resources; over-assessment is easy to plan and wasteful to implement.In fact, assessment in PBL is no different fromassessment in general: if you decide what it is for,you are likely to make a better job of it [22].

Figure 12. The Maastricht Seven Steps (adapted from theBritish Medical Journal, BMJ 326 (7384) (2003), p. 328(8 February), doi:10.1136/bmj.326.7384.328; http://www.bmj.com/cgi/content/full/326/7384/328).

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Let us look at some possible reasons for assess-ment. Competence is most readily related to theacquisition of skills. PBL provides an excellent frame-work for the development of skills but it is not a goodmethod of skills instruction. For example, a practicalproblem might require the use of an oscilloscope.Students need to know that such equipment exists andhave access to an instruction manual or a workshop onits use. The assessment might expect them to reach athreshold level of competency. The PBL problem willmotivate and reinforce the acquisition of this skill, butwill not leave students to discover it for themselvesas part of the problem. This point may seem obvious,but it is sometimes missed by critics of PBL. We havefound that the same conclusion applies to mathema-tical methods in physics [23].

Likewise the purpose of assessment in a trainingcontext is to give feedback. It is confusing if this ismuddled up with gathering marks that are supposed tobe distributed (normally or otherwise): in competencybased assessment and training everyone should begetting close to 100%, at least eventually. Then thereare different grading exercises one might want to carryout. There is a distinction between progression (pass allbut the worst) and selection (fail all but the best).Using selection tests for progression can lead simply tomarking random noise at the progression boundary.

Our experience is that awareness of these distinc-tions can simplify the assessment load for both staffand students. For example, if process assessment is forcompetence, there is no need to carry on with it oncecompetence is demonstrated. This can reduce theassessment workload.

As discussed above, constructive alignment is akey feature of curriculum planning. One of its mostimportant ingredients is assessment. Students arelargely assessment-driven. If the assessment does notrequire students to solve the problem then it willundermine the PBL approach. We would go further: ifthe assessment asks students to behave as students andnot as professionals, then the professional framework

of the PBL problem is largely redundant. A typicalexample of unaligned assessments is the grouppresentation. If the problem context does not requirea group presentation then adding one on purely forassessment purposes undermines the attempt toinculcate professional values.

Here are a couple of examples where presentationsare integral to the problem. We call this approach‘authentic assessment’. In a telescope project studentsbuild their own simple refracting telescopes with aCCD detector (a webcam in fact) and use it to observea simulated eclipsing binary star system on a computermonitor at the far end of the laboratory. Since theirtelescopes are unique, so too are their observationsand, in particular, their calibration of the detector.No one can tell them if it is correct. However, theobserving time for each group is much less than abinary period, so to get a complete light curve, andhence to deduce the properties of the binary system,groups must exchange data. They do this at aconference where they submit their partial results.Their data will be of use only if they have calibratedtheir detectors correctly. Thus, students are motivatedto carry out the task correctly, and check that theyhave done so, not just for the purpose of gaining marksbut in order to interact in an authentic way with theirpeers.

The detection of leaking water pipes in the desert(Figure 5) provides a similar set-up. Groups have toexchange data on the refractive index of wet and drysand, determined by measuring reflectivity in variouswavebands, to see if this could provide the basis for theremote detection of leaks.

These two assessments were by oral reports. Acouple of examples of authentic written assessmentsare a patent report and a report for an insurancecompany. The form of the report on the patentapplication that we require is somewhat simplifiedfrom the real thing (as is the patent application thestudents get) but is nevertheless a simulation of a real-world output that can be assessed. The insurance scam

Figure 13. The first year physics class (left) working on the problem in Figure 1 and with ‘floating’ facilitator (right).

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problem (Figure 8) requires a report for an insurancecompany on a set of experiments that will allowanother laboratory to determine the authenticity of anartefact, not just another ‘laboratory report’.

In PBL it is common practice to assess process aswell as content (and to support the development ofprocess skills by relevant feedback). Many PBLimplementations structure group work by assigninggroup roles for meetings: someone to chair themeeting, someone to keep the minutes, someone tokeep an eye on the schedule, someone to check foraccuracy and so on. In some situations this works well.For example, in the Physics programme at Leicester wehave a management course in which students run acompany. Their board meetings are most effectivelymanaged if there is an acknowledged chair andsecretary and everyone else has a designated role inthe company. In the Finnish system [24], for eachmeeting a member of the group is assigned to the roleof observer, whose job it is to evaluate the performanceof the group individually and as a whole, and providefeedback. Generally though, many tutors find assignedgroup roles tedious, with a tendency to generate over-assessment. The problem we think arises from theartificial nature of group roles. Students know that,with the possible exception of a chair and secretary,their teachers do not do this in their research meetings.We usually just get our facilitators to assess ‘engage-ment’ at group meetings on a very simple scale (‘veryeffective’, ‘sufficient’ and ‘not a lot’). But we also askgroups to keep a written project plan, or projecttracking form, in which they track who is doing whatand what has been done.

The problems of group assessment are not specificto PBL so we shall be brief. Generally a report orpresentation will be a group responsibility and thegroup will get a single mark. If the problem requiresthe contributions to be divided (for example contribu-tions from different stakeholders to a single report)then it is clear how to divide the marks. A problemarises when the contributions to a group report are notequal. The marks can then be weighted by some formof peer review or peer assessment. We also use aweighting related to attendance at scheduled groupmeetings.

It is perhaps useful to remember that PBL usesgroup work to aid learning. It does not follow thatassessment has to be by group. It would seem odd ifthere were no feedback to the students on theirsolution of the problem, but there does not have tobe an assessed report or presentation if this is notaiding their learning in a way that justifies theresources. PBL is an alternative pedagogy by which(among other things) students learn the same disciplinecontent as by any other approach. If all that is at stake

is this subject knowledge and its applications to solvingproblems then there seems to us to be nothing wrongwith a conventional examination (provided, of course,that simply working through the past papers does notbecome a more effective examination preparation thanthe PBL activity).

6. Evaluation

PBL provides an environment in which cooperativelearning can take place. The gains from collaborationare well known (Figure 14) [25].

A large number of studies have been carried out totry to determine the effectiveness of PBL moregenerally. In Physics strong positive results in favourof PBL curricula in terms of both student achievementand retention rates have been reported. Duch et al. inDelaware [26] have demonstrated high gains in concepttests in introductory mechanics for PBL over tradi-tional methods. Bowe in DIT Dublin [27,28] hadthe opportunity to compare PBL and conventionalteaching of the same material to a split cohort of year 1students. He found an improvement in studentengagement and retention rates in the PBL group.Lennon in Dundalk [29] found a significant improve-ment in performance in a first year physics class onswitching to PBL. McLaughlin and van Kampen inDCU, Dublin [30] found that the benefits of PBL in athermal physics class continued to subsequent tradi-tionally taught courses in terms of student engagementand self-direction. Moran in Liverpool [31] foundgreater engagement in a PBL version of her course.Kohlne9 in St Andrews has also used PBL to promotestudent engagement in physics.

On the other hand, several surveys have reportedno gains from adopting PBL (e.g [33] but see also theresponse by Hmelo-Silver et al. [34]). There are tworather obvious difficulties in evaluating PBL in

Figure 14. % gains in traditional teaching and co-operativelearning compared. Redrawn from Hake [32] withpermission. Only the results for university students arereproduced here.

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addition to the usual novelty effect. One is the problemof comparing like groups of students, particularly inview of the ethical problem of dividing a given cohort,other than voluntarily. The second is in deciding thecriteria for success: the original principal aim of PBLwas to train better doctors not to get better examina-tion results.

A number of meta-studies and reviews have beendesigned to put together the data from individualinvestigations. In a recent comprehensive review,Strobel and van Barneveld [35] summarise the resultsfrom a selection of eight of these meta-studies, whichtogether include a total of around 160 investigations.The majority are in medicine and professional educa-tion (including teacher education where the largestpositive effects in favour of PBL seem to be present).The authors find that the outcomes depend on what ismeasured: PBL was superior for long-term retention,skills development and satisfaction of students andteachers; traditional approaches were more effectivefor short-term retention as measured by standardisedexaminations.

Our own external evaluations of those parts of theLeicester programme taught by PBL have shown along learning curve in getting the implementationright, which turns out to be a common problem notmuch discussed in the literature (although see some ofthe case studies in Schwartz et al. [36]). One way tomeasure success is in terms of the level of engagementand understanding demonstrated in the student re-ports. We find that success in these terms is heavilydependent on the quality of facilitation (although it isnot possible to disentangle this entirely from potentialinadequacies in the problems, since both might haveimproved with experience). For success factors in PBLsee Barrett [37]. We also find that students grow toappreciate PBL over time:10

‘we felt we needed preparation for PBL but, actually,PBL was a preparation for now’ – (3rd year studentafter two years with PBL).

Acknowledgements

The development of PBL at Leicester has been fundedthrough University of Leicester teaching development grants,the HEFCE FDTL programme, the CETL programme, theIOP Stimulating Physics programme and more recentlythrough the HEFCE STEM project.

Notes

1. http://fnoschese.wordpress.com/2011/02/21/pt-pseudoteaching-mit-physics/

2. One might argue that the Oxbridge tutorial systemachieves precisely this; but this is problem-solving notPBL (see below).

3. ITUE, University of Delaware.4. Versions of the student laboratory scripts for the

example problems are available as Open EducationalResources at http://dspace.jorum.ac.uk/xmlui using‘core physics PBL’ as the search term.

5. A set of problems covering the typical English andWelsh year 1 syllabus (and somewhat beyond) can befound at http://www.physics.le.ac.uk/ProjectLeAP/.

6. Although we have met one person who claims to digestthe whole of Nature each week.

7. http://www.learningandteaching.info/learning/assimacc.htm.

8. http://www.learningandteaching.info/learning/constructivism.htm, http://tip.psychology.org/vygotsky.html.

9. A. Kohnle, 2009 Talk given at PHEC 2009(unpublished).

10. A description of the PBL Physics programme atLeicester can be found at http://www.physics.le.ac.uk/ProjectLeAP/ together with external evaluation reports.

Notes on contributors

Derek Raine is Professor of Interdisciplin-ary Science in the Department of Physicsand Astronomy at the University of Leice-ster, and director of p CETL, the PhysicsInnovations Centre for Excellence in Teach-ing and Learning through which a majorpart of the development of Problem-basedLearning has been carried out under the

direction of the authors. The authors began their collabora-tion on the implementation of PBL in Physics in 2002 withthe HEFCE funded Project LeAP and subsequently devel-oped the Interdisciplinary Science programme at Leicester,which is taught wholly through PBL. Professor Raine wasawarded the Bragg Medal of the IOP for his work oncurriculum development through PBL and is an HEANational Teaching Fellow.

Sarah Symons has a Ph.D. in the His-tory of Astronomy from the University ofLeicester. She has six years experienceof managing teaching and learning pro-jects in the physical sciences in the UK.She is now assistant professor in theDepartment of Physics and Astronomyat McMaster University, where she is

collaborating on the development of the IntegratedSciences (iSci) programme.

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