Is Problem-Based Learning Effective for Teaching Science Subjects?

[handsomecat]

For my curiosity and perhaps to start a discussion in this forum,

(1) Has anyone used Problem-Based Learning to teach science subjects?

(2) Has anyone experienced Problem-Based Learning in a science subjects?

(3) Any thoughts on PBL?

this would be a good intro to PBL:
http://en.wikipedia.org/wiki/Problem-based_learning

 

[Andy Resnick]

We exclusively use problem-based learning here in the Dpeartment of Physiology and Biophysics, so I've taught material (in some cases, the same material) both in a lecture-based and dialectic-based format.

PBL can work extremely well under the following assumptions:
1) The class size is small: between 8 and 12 students.
2) Students have read the material and come to class able to discuss.
3) The 'facilitator' does not lecture.

PBL will not work for presenting certain materials: standard derivations of well-known results, for example. PBL also requires a lot more work on the part of the faiclitator prior to the classes.

When PBL works, it's amazing.

 

[handsomecat]

PBL can work extremely well under the following assumptions:
1) The class size is small: between 8 and 12 students.
2) Students have read the material and come to class able to discuss.
3) The 'facilitator' does not lecture.

So the resource material is assigned beforehand ? Are they constrained to that resource material?

How old are the students?

I'm joining a department where PBL is used exclusively, hence this post.

 

[Andy Resnick]

I can't speak for other departments- here, resource material is assigned beforehand and class discussion is not limited to the resource material.

This is grad school, if that matters.

 

[handsomecat]

I see, thank you, that's really interesting. I'm with an institution that uses PBL with students just out of junior high school (to use the american description).

I've kinda had enough with the lecture-tutorial method. I've given really simple problems during tutorials after a very good lecture by the prof, and yet I have students staring blankly at the paper, or struggling with concepts that we take for granted that they should already have.

It made me question whether the problem lies with the system, instead of the students.

 

[Beeza]

I have absolutely hated every PBL-style course I've had. I'd much rather sit and listen to a lecture than work through some mickey-mouse worksheet with whatever idiot you get stuck sitting next to.

 

[Oxymuon]

Your students will never have as good a grasp of the underlying ideas if you go exclusively with PBL. The best experiences that I have had were of lectures that were organized and kept track of the overarching ideas. Examples were always nice as supplements, but I have personally disliked every single class that used PBL more than absolutely necessary.

 

[handsomecat]

Your students will never have as good a grasp of the underlying ideas if you go exclusively with PBL.

hmm, do you say this based on your experiences?

 

[Oxymuon]

hmm, do you say this based on your experiences?

My experience as a student. Once I really understand an idea, I have no need for a variety of examples. The only reason that such need arises is if the lecturer has failed to clearly deliver the concepts. So instead of going with PBL (which can only develop students with great technical skills who will forget what they learned a year later because all they have grasped were techniques), I would strongly suggest developing a curriculum proceeding from the general ideas down to the applications, and let the students work out examples in their own time.

 

[Andy Resnick]

I wonder if we are all talking about different types of "PBL".

For my classes, students spend the majority of 'learning time' outside of the class- classroom time is spent on the few topics the students are having trouble with. We don't spend time on worksheets in class.

Class time is a lot like a journal club meeting (if anyone here has done that). My tests are completely open-note, open-book, open anything: they are take-home, and I tell the students they may collaborate, talk to anyone they want (including professors and students who have already taken the class), whatever.

Handsomecat, can you give any details on the class you are designing (topics, class size, etc.)?

 

[handsomecat]

yes, I certainly could give more details. That will have to wait a week or two, as essentially I will be one of the junior staff that's just facilitating the sessions. I'm still discovering and learning the system :)

What I can say now is that the institution is tertiary-level but for students aged 17 and above. Class size is a maximum of 25.

 

[Moonbear]

I have absolutely hated every PBL-style course I've had. I'd much rather sit and listen to a lecture than work through some mickey-mouse worksheet with whatever idiot you get stuck sitting next to.

What you're describing is NOT PBL.

We use PBL for some of our medical courses. It's very effective to supplement their education. In our case, we give them the cases they'll discuss when they come into the class on any given day, they work through it together and figure out as much as they can, and set up their own learning issues to research as their "homework" for the next week, when they get the next part of the case. Each case lasts 3 weeks. During the class on the last day of each case, they develop a concept map relating all the things they've learned over the course of that particular case...this helps them identify gaps in knowledge, and show them just how much they have learned, and makes all the connections between concepts that may not have initially been learned in a structured order.

As Andy points out, the biggest downfall (and when students dislike PBL) is when the facilitator switches into lecture mode instead of just keeping everyone on task (my most common intervention as a facilitator is when they're all staring at each other unsure of the answer to a question someone posed, and I suggest it might make a good learning issue).

The stuff my students learn in PBL is likely to stick with them better than passive learning in a lecture.

It's certainly not about doing worksheets together in pairs, it's about having group discussions to learn as a team while discussing a relatively complex problem you wouldn't do individually. This worksheet discussion sounds more like the small groups we do that go over homework problems...we're actually planning on dropping that part of the curriculum because students don't seem to get much out of it, and we don't have enough faculty to put the time into it.

And, of course because I teach med students, this course also is teaching them to work in teams, which they will need to do in clinics as well.

Our groups are about 8 students in size. When they start getting much larger, they lose some effectiveness due to not everyone getting a chance to really participate, and when they get smaller, there aren't enough people to contribute to discussion to keep things moving along.

I recommend anyone wanting to set up a PBL based course visit a place where it is already being used and observe a good facilitator and group to see how to do it and how to train your faculty to run your course. Our course coordinator did that and attended some workshops specifically on conducting PBL, and then does a staged PBL session with experienced facilitators playing the role of students to train newcomers. The quality of the facilitator can really make or break the effectiveness of the class.

 

[Moonbear]

PBL also requires a lot more work on the part of the faiclitator prior to the classes.

I've actually found that it works best when I put very little advanced effort into it, which makes it very easy to teach. I just skim the case over about an hour before going to the class to make sure I know where it is going so I can intervene if students get too far off onto a tangent, but the less I prepare, the more work the students have to do for themselves.

Oh, I just thought of one other thing. I let the students look up some stuff during the session (we have internet access in the classrooms), but my rule is that during discussion, laptops are closed, and if they need to look up something, only ONE is opened that they share. This ensures they are all talking to each other and not hiding behind computer screens, but still have access to the internet to look up sources (if it's a lengthy question, it becomes a learning issue, but if it's a short question, like looking up the definition of a term that's preventing them from getting further into the depth of the discussion, then I allow that).

Mostly, I just set my B.S. filter to pick up when they're guessing at answers without indicating to the group it's a guess, and make them double check those answers, but I never give the answer to them...so I don't even need to know what the answer is myself.

 

[Andy Resnick]

Moonbear,

I like the idea of having students turn off the computers during class- I think I'll start doing that.

As far as preparation, I admit I merely skim the material prior to class as well. The amount of time I put into organizing the 6 classes into a coherent whole- selecting the reading material, preparing the class notes (distributed prior to class), etc. is slightly more than I do for lectures.

For the med students- things are a little different. In the PhD program, it's based on semester courses, with homework and tests- just like any other undergrad class, other than the teaching style. In the MD program, the curriculum is totally bizarre (from my perspective). It's based on 10 week "blocks", each block contains large, medium, and small groups. There is a 'block leader' that coordinates *all* the activities for the block, and there are medium group leaders and small group facilitators. The powers that be request that small-group facilitators are non-experts (something I disagree with, but whatever). That means that the block leader not only has to come up with the material for the students, lead 1 or 2 2-hour lectures where the material is introduced, but also has to come up with the "teacher notes" for all the facilitators, and the good leaders also schedule a prep session for the faciliators to go through the small group PBL session to calm the facilitators down and get them prepped for the small group.

And then the administration wonders why they can't get enough block leaders...

 

[Moonbear]

Moonbear,

I like the idea of having students turn off the computers during class- I think I'll start doing that.

As far as preparation, I admit I merely skim the material prior to class as well. The amount of time I put into organizing the 6 classes into a coherent whole- selecting the reading material, preparing the class notes (distributed prior to class), etc. is slightly more than I do for lectures.

Yeah, since the PBL I do is all for med student courses, the course coordinator gets stuck with that burden, not the faculty facilitating the groups.

For the med students- things are a little different. In the PhD program, it's based on semester courses, with homework and tests- just like any other undergrad class, other than the teaching style. In the MD program, the curriculum is totally bizarre (from my perspective). It's based on 10 week "blocks", each block contains large, medium, and small groups. There is a 'block leader' that coordinates *all* the activities for the block, and there are medium group leaders and small group facilitators. The powers that be request that small-group facilitators are non-experts (something I disagree with, but whatever). That means that the block leader not only has to come up with the material for the students, lead 1 or 2 2-hour lectures where the material is introduced, but also has to come up with the "teacher notes" for all the facilitators, and the good leaders also schedule a prep session for the faciliators to go through the small group PBL session to calm the facilitators down and get them prepped for the small group.

And then the administration wonders why they can't get enough block leaders...

This seems to be the common theme in med schools...took me the last 3 years to grasp what was going on too...I think I finally figured out their curriculum, and now they're planning to change it! Plus, there seems to never be a fixed schedule. The students just know they're there from morning 'til evening every day, but it seems as we try to integrate some clinical experiences into their first two years, the schedule gets more and more disrupted by the clinical faculty who like to change things on a whim and then expect the basic sciences faculty to adjust our schedules to fit with that. The students don't like that very much either...they'd prefer to have a weekly routine, and it disrupts them as much as us to have the clinical faculty suddenly decide instead of a Friday meeting, they should have a Wed meeting.

We have a good "bank" of cases for PBL, so it's not too much of a burden anymore. The facilitator notes are already prepared in the "tutor copy" of each case when the case, and updated based on our reviews each year (both the students and faculty give a review of each case to the course coordinator; sometimes it's catching errors or outdated treatments...oops, the one the case is talking about is now banned in the US...and sometimes it's more substantial comments about insufficient information, too much information, bad timing relative to their other courses, etc). All of the faculty contribute to developing cases over time (though a few took on much more of that burden to get the course started). Right now, I'm starting to develop a case, but since there are plenty of others, there's no rush and it doesn't have to interfere with other things I need to get done...it's more like a hobby to work on it than actual work.

None of us is an expert in all these topics...though I have fun learning along with the students...how important that is depends on how heavily dependent the curriculum is on PBL. In our case, PBL supplements traditional lecture and lab based coursework just to start introducing the students to clinical thinking while we still have them in the firm grasp of the basic science faculty to emphasize the importance of the basic sciences in medical practice.

Other places heavily rely on PBL for much or all of their curriculum, and then I think it becomes more important to have more expertise among the facilitators since they aren't going to have another place for feedback on whether they're getting it right or wrong before the Shelf exams. Though, my impression is that having a curriculum heavily based in PBL is a good way to waste faculty resources...the students still seek out the faculty, but instead of giving a single lecture on a topic, you have groups of students trickling into your office all week long and you have to repeat the "lecture" 10 times.

I don't use PBL format for graduate student teaching, though I guess I borrow *some* aspects of it. I do like the journal club format of teaching for them, but it's more that either I or a pre-assigned student presents an overview of the paper(s) in a lecture-ish format, and then it opens for round-table discussion. For me, that does take more preparation time (some faculty put no effort into it and just grab whatever journal articles they just happen to be reading when they need to send out the reading list to the students I think). I like to have at least 3 papers on a topic for a class that are in some way cohesive yet highlight different approaches, be it different models or opposing hypotheses on a controversial subject, or something cutting edge and something more classical, and of course I make sure I dig into all the "back story" that goes with each...the students should be doing so too, but if they don't I want to make sure I have done so to point out what they missed by not checking references or learning the full story the paper is based upon. Sometimes, simply finding 3 current papers on a topic that are of sufficient quality to teach from can be the biggest part of the challenge (though I'll throw in a bad/flawed one from time to time just to get the students to realize they need to read critically).

Oh, and when you wonder where the dept chairs come up with odd ideas, look no further than the chairs meetings they attend in those nice tropical locations mid-winter. They all compare notes then and need to "keep up with the Jones'" so to speak. I think the deans do the same thing, but at their meetings, they compare numbers of training grants and new buildings going up as measures of success.

 

[handsomecat]

well, looks like you guys have PBL with more mature students. At where I work, its all kids, from 17- year olds.

You can also probably see that on a large scale, it is very labour-intensive. There are almost 200 classes each week to handle, and the problem briefings have to be spread over two separate sessions.

 

[Moonbear]

well, looks like you guys have PBL with more mature students. At where I work, its all kids, from 17- year olds.

You can also probably see that on a large scale, it is very labour-intensive. There are almost 200 classes each week to handle, and the problem briefings have to be spread over two separate sessions.

I started a thread that didn't get any response yet on team-based learning. It's meant for larger groups, and might work better with younger students (I think it's more structured). I don't know if the thread is still on the first page here. Anyway, I had a link in there to some information on it. I'm trying to learn more about it too for situations where there aren't enough facilitators to break down into small groups or PBL sessions, but where inspiration of more active rather than passive learning is needed beyond what I can do by simple Q&A in lectures. This might suit your situation better than PBL too.

 

[handsomecat]

Handsomecat, can you give any details on the class you are designing (topics, class size, etc.)?

Yes. I'm just one of the many many facilitators in the department. The staff take turns to design the problems.

Topics: general science . The kind that Junior High school students would have encountered. physics, chemistry, biology.

Time frame for each problem: one day.

Class Size: 15 to 20.

Team Size: 3 - 5.

Problem: presented as a scenario, issues to address are provided clearly.

Resources provided: a worksheet, internet access (mostly used), library (rarely used!),

 

[symbolipoint]

handsomecat, I once developed and scrounged for Introductory Algebra ideas for group & pair exercise problems for linear equations. Internet would not be needed - just pencils, straight edge or rulers, graph paper, and maybe a calculator. Each group would be given a brief , exact description on paper and would then do some activity, either to make a graph and determine some values, or use a graph to give conclusionary information. I never actually had enough opportunity to try the ideas in practice, but maybe others would.

 

[vanesch]

I have a question concerning what you guys consider PBL. As far as I understand, genuine PBL is based upon the axiom that by solving, or struggling to solve, problems you didn't get the tools for, you'll invent them yourself, and you will integrate them much better than if someone explained the concepts to you. This is like confronting, say, students who only have algebra knowledge, and never had any calculus, with a problem where you need to calculate a derivative or an integral or something, and then let them struggle until they find a way out (and re-invent, or document themselves, or whatever) calculus. So they should then surf on the web, visit the library, do whatever is needed to solve their problem, and at the end of the day, they've learned some calculus.
Is that what is PBL for you ?

 

[handsomecat]

I have a question concerning what you guys consider PBL. As far as I understand, genuine PBL is based upon the axiom that by solving, or struggling to solve, problems you didn't get the tools for, you'll invent them yourself, and you will integrate them much better than if someone explained the concepts to you. This is like confronting, say, students who only have algebra knowledge, and never had any calculus, with a problem where you need to calculate a derivative or an integral or something, and then let them struggle until they find a way out (and re-invent, or document themselves, or whatever) calculus. So they should then surf on the web, visit the library, do whatever is needed to solve their problem, and at the end of the day, they've learned some calculus.
Is that what is PBL for you ?

Well PBL is based on the idea that students need to construct their own knowledge and find their own meanings for them. So yes, this is vastly suitable for subjects like engineering due to the problem-solving nature of the subject, and the humanities due to the diversity of ideas possible, but I'm not sure how it is applicable to maths and calculus.

 

[vanesch]

Well PBL is based on the idea that students need to construct their own knowledge and find their own meanings for them. So yes, this is vastly suitable for subjects like engineering due to the problem-solving nature of the subject, and the humanities due to the diversity of ideas possible, but I'm not sure how it is applicable to maths and calculus.

Well, there's a difference between case studies to put into practice the theoretical basis you've learned already and to devellop problem solving skills, and struggle with case studies to derive, on your own, the theoretical basis. The former is like doing a research project or a PhD (which is nothing else but PBL in your area of application), while the latter is, well...
Even in engineering, I have a hard time thinking that one would learn, say, electromagnetism on one's own by fiddling around whole day in the lab with apparatus that you don't even know how to use.

In fact, my wife is studying this as part of her PhD (that's how I got interested in this stuff). In France, since about 10 years or so, classical languages are taught this way: not much vocabulary or grammar, but just the original text and a translation in juxtaposition. And from that, the student has to "learn how to translate", or even better "learns how to read the original". It is a complete disaster, and part of her work is the analysis of that disaster. An experiment has been performed where one has compared the performances of students who never had any exposition to Latin courses with those who had courses for 4 years, and the result was that both groups performed almost identically on the tests

So in as much as one can learn skills this way, I wonder how much you can gain structured knowledge, purely based upon PBL. It's entirely different if you already have (more or less) the theoretical basis to solve the problem.

 

[Moonbear]

So in as much as one can learn skills this way, I wonder how much you can gain structured knowledge, purely based upon PBL. It's entirely different if you already have (more or less) the theoretical basis to solve the problem.

In our program, all of the PBL classes have facilitators to help focus and guide discussion. So, the students aren't entirely on their own. Still, the key to getting it to work well for them is 1) to have well-crafted cases that will lead them toward questions they should be asking, and 2) having good facilitators who only keep them from going astray and resist the urge to interrupt and give a lecture, and 3) cases that supplement the formal lecture courses, so they have some fundamentals going into the class.

However, there are programs that really leave the students on their own. The only reason they work for those students is that the faculty are driven mad with each and every group coming to them separately, asking questions and seeking guidance, rather than just giving one lecture to all of them on the topic. So, I think it's a myth that they really are learning without lectures, it's just individual lectures given over and over and just increasing faculty time rather than helping reduce the time the faculty need to put into the course.

 

[Moonbear]

I had another thought this morning regarding Vanesch's question about how PBL students learn the basics. One thing we have to watch out for as facilitators in our groups are the "medical experts." These are students who have more than the average experience in the topic before we start, either because they had EMT or paramedic training before entering med school, or parents who are physicians, so grew up hearing about this stuff all the time, or some other form of experience that better prepares them than average students. The reason we have to watch out for them is that they can quickly dominate discussion, basically turning it into a one-person show lecturing to everyone rather than everyone taking time to think about the problems and discuss it as more of a team effort (part of our goals with the course go beyond the content and include the teamwork and communication skills development, which it is well-suited for).

As I think about that, it occurs to me that these "medical experts" in the class might be what makes PBL effective in places that don't offer traditional lectures. They may be the ones providing the lecture. I suspect that if you eliminated those from your group, and all students were naive to a topic upon starting, that PBL wouldn't be very successful at all, at least not without a facilitator present to prompt them to consider the right questions.

 

[Astronuc]

Well PBL is based on the idea that students need to construct their own knowledge and find their own meanings for them. So yes, this is vastly suitable for subjects like engineering due to the problem-solving nature of the subject, and the humanities due to the diversity of ideas possible, but I'm not sure how it is applicable to maths and calculus.

Ummm - much of engineering is math and calculus, so how would PBL be suitable to engineering, but not to math and calculus.

With regard to concepts like convective heat transfer and turbulence, and many other aspects of engineering, I'm not sure how one would turn a student loose without some lecture on the basic physics, which is also heavily involved in math and calculus.

Most of my course work was lecture based, with problems. The problems were pretty intensive and we often worked in groups to work a problem out. Often one had to extrapolate from the theoretical to applied in order to work a problem. It was rarely, plug and chug - especially when it came to design and analysis.

 

[Moonbear]

Ummm - much of engineering is math and calculus, so how would PBL be suitable to engineering, but not to math and calculus.

I think what he's suggesting is that students would get the lectures on math/calculus, and then PBL would be used for applying it to engineering problems.

But your question also gets at the point Vanesch brings up, which is that in a true PBL-setting, where do we expect the students to acquire the knowledge?

There are a lot of faculty who like to just jump in and use the newest teaching methods just for the sake of looking innovative, and don't really consider if they work, and if they would work for the particular group of students they have and the course objectives.

At least one advantage I see of TBL over PBL is that in TBL, the questions students need to be able to answer are given to them, so they have at least that much structure in identifying topics to study. In PBL, it is entirely student-directed learning, and there's really no check that they are getting the information they need.

My view on PBL is that it is a really nice supplement to a curriculum where students can practice their critical thinking and communication skills, learn to work on a team, and learn to apply what they've learned in their classes. When I say curriculum, I don't mean for a single course, I mean in the context of all the courses one is required to take for a particular major or degree. For example, our medical students still have standard course lectures on physiology, biochemistry, histology, anatomy, pharmacology, microbiology, etc., and PBL is just one extra course that gives them some practice applying all these topics together and understanding the conceptual relationships among them for the practice of medicine. I would NOT want these cases to be their only source of information for learning biochemistry, physiology, histology, etc.

I also think that PBL would be an excellent tool in a graduate program curriculum. When the goal of graduate school is no longer information-based education, but really rounding off their development of self-directed learning and learning how to research topics on their own, and where the specific knowledge the get out of a course isn't terribly important, as long as they are learning SOME topic in great depth, then this could be very useful.

 

[Astronuc]

PBL is a new term to me. I taught by lecture and problem assignments, which is pretty much the way I was taught.


I guess one has to look at the entire picture, starting in K or 1st grade. In primary education (1-6), it's pretty much lecture and doing activities, and it's mixed subjects (3R's + humanities + science) with one teacher. Starting in grade 7 (or middle school/junior high school) the classes become specialized/differentiated and each teacher teaches a particular subject. The learning there is based on the foundation of knowledge from earlier grades.

Presumably, the upper level university classes are built on the foundation of the lower level classes. In engineering or even advanced phsyics, I'm not sure how a strictly PBL approach would work.

What's TBL, btw? Textbook?

 

[symbolipoint]

Some commentary from Astronuc:

PBL is a new term to me. I taught by lecture and problem assignments, which is pretty much the way I was taught. ...

An example of PBL (problem based learning) would help to understand what it is/can be.

Students in a science course can pick an activity (or problem) from a list, and find out how to solve or design to satisfy that listed description. The student may need some procedural guidance but the work must be the student's. Some library search may be needed. Or as possible, a Microbiology student may be given the task, "collect some microbes from the environment, cultivate them, and identify and characterize two of them (the student would need to use their instructed, learned course skills to do this).

An students in an organic chemistry class may be given any of individual synthesis projects, randomly from a set; each student picks a compound as is then expected to do a literature search for methods to synthesize and then to try synthesizing the compound, and then extract or purify, and analyze his results. He may find more than one of a set of somewhat similar variations or alternate variations of literature articles describing how to synthesize the chosen target, but the student must make his best choices according to what may be available for his laboratory.

A computer science course (maybe even a beginning course) may later in the semester, make a list of possible project ideas (problems, actually) for students to choose and solve/write programs for. These would be much longer programs than the typical course exercises used in chapter assignments or lab section activities. Instead of writing a program focusing on just two or three new concepts and using some other learned concepts and going up to maybe 200-250 lines of code, the project would require maybe two weeks and go up to maybe 1200-2000 lines of code, and the problem description is more detailed than a typical course chapter exercise. Also, student would receive no guidance (even may need to relearn already studied material).

One point of possible misunderstanding: Is PBL a mode of instruction for an entire course? If so, I find this possibly a little troubling. Maybe other viewpoints are needed.

 

[symbolipoint]

... in fact, maybe I have most of the concept but PBL is really applied to the WHOLE course. Is this true?

 

[Moonbear]

One point of possible misunderstanding: Is PBL a mode of instruction for an entire course? If so, I find this possibly a little troubling. Maybe other viewpoints are needed.

Yes, PBL would be for an entire course. I don't think what you describe would be considered PBL. What you described are more independent research projects.

An example of how we use it. The med students are given a case that spans three weeks, with them receiving another part of it each week. They are basically presented with a fictitious patient's medical records. The first week usually starts out with a patient history, description of symptoms/presentation, and some basic lab test results. The students are then challenged to start diagnosing the patient. BUT, it goes beyond this (sometimes we even give them the diagnosis in week one). They also need to formulate, as a group, a set of learning objectives about the basic science issues they need to learn to understand HOW the symptoms relate to the illness. So, for example, if the case tells them a patient has X illness and is put on Y medication, they need to go find out the pathophysiology of illness X all the way down to the biochemical mechanisms, how it affects other organ systems aside from the one directly addressed in the initial presentation of symptoms, and the mechanisms of action of drug Y for treating that illness.

By the time they are done with three weeks of work, they develop a concept map, and basically find out they've learned the anatomy, physiology, biochemistry, microbiology, histology and pharmacology related to an entire organ system...or, sometimes they learn that they have a LOT of missing information they didn't learn that they should have.

There are med schools that use this entirely as their basis of instruction and offer NO lectures at all.

Astronuc, TBL means team-based learning. There is another thread on that. It's more formal, includes things like pre- and post-tests, and students don't have to come up with their own questions, but work as a team to find answers to pre-assigned questions. With PBL, the group works in isolation from any other groups. In TBL, the groups work together, but then share answers with the larger class so all can benefit from the cooperative effort. I think TBL is more suited for the less mature learner (and by mature, I don't mean behaviorally or age-wise, but in terms of experience and background). PBL, in my opinion, is best suited for the more mature/advanced learner.

The problem I have with most of the literature on these teaching methods is that they are poorly controlled. For example, as a measure of outcome, they might use passing rates on board exams. However, the comparison is made between historical passing rates from previous classes, and then current passing rates with classes converted to PBL. There is no way to know if OTHER factors have influenced those passing rates, such as changes in admissions criteria, differences in undergraduate curricula of those admitted, students being threatened by the dean that previous classes haven't done well and that they need to study harder for board exams, differences in board exams over the years, etc. It could even be like the course I'm teaching, in which previous instructors have been, to say the least, horrendously boring and confusing, and new instructors come in and ANYTHING could be better for improving their outcomes. This is why I'm trying to build in some controls with my approaches discussed in the TBL thread, such as only using it in some, but not all lectures, so I can compare differences in content learned when I lecture ONLY vs when I lecture and then add on TBL learning. I'm also attempting to collect survey data AFTER the course ends that includes a brief test of course content to find out if student retain the information better, which is really the true goal any instructor should have.