The Real Purpose of PBL

Like many of you, I took biology in 9th grade.  Never having taken another biology or anatomy course in my educational career, I am ashamed to say that there is much that I have forgotten.  One detail that pops into my mind every once in a while is that a mitochondria is the powerhouse of a cell.  I am not sure exactly what that means, or how the mitochondria works, or how something as small as a cell has so many smaller parts to it, but I am pretty sure that I am correct about that fact.

Why do I remember that fact?  Is it because my biology teacher was amazing? Perhaps.  Is it because I remembered some mnemonic such as "mighty mitochondria"?  Could be.  Is it because Julie Mitochondria was the name of the girl that I secretly had a crush on throughout high school?  Unlikely.

No, the real reason that I remember this random fact is that at some point I stayed up late studying for a biology test, memorizing all of the parts of the cell and their functions just well enough so that I would be able to regurgitate that information the next day on the test, and probably again six months later on the final.

Fast forward to today.  Like most other teachers, I still give tests from time to time.  Being a reasonably good teacher, I try to pack my tests with questions that will test not only my students' ability to memorize, but also their ability to think, to process the material and use it to answer a question that is somewhat different than the exact way that we learned the material in class.  However, I inevitably find students who are capable of providing answers that touch on the correct information, that come oh-so-close to actually demonstrating real understanding, but who nevertheless produce a response that shows that they are still collecting information points without truly comprehending what connects them into one larger system.  In my earlier example, I can explain the function of the mitochondria and the nucleus and the ribosomes, but I cannot quite explain (in my own words, of course), how a cell functions.

To my mind, this is ultimately the most important contribution of Project Based Learning (PBL) to the business of teaching.  My biology teacher (note - she was a wonderful teacher; I'm just picking on the subject since it is an area that I completely avoided, regrettably so, for the rest of my academic career) wanted me to understand cells, so she tried to build my understanding from the bottom up, hoping that by understanding each part, I would understand the whole.  Project Based Learning, by contrast, starts from the end and works backwards.  A driving question for that cell unit would be something along the lines of "What are cells and how do their discrete parts work together to sustain life?"  A culminating project that asked me to consider various diseases that afflict cells and how they do so would drive me to understand each part and what a deficiency in that part would mean for my overall health.  There is no way that writing down a few key words in the right place would get me "partial credit" for an assignment such as that.

When reconfiguring existing units to be PBL units, my longest stretches of creative thinking focus on exactly this point - what am I really trying to teach in this unit?  As a teacher of religious and legal texts, the answer is not always so obvious since the texts (Torah, Talmud) are not always divided up topically as easily as a Biology or a History textbook might be.  At times I need to combine parts of what were previously distinct units or break apart one unit into smaller pieces so that I can focus my students on one or two essential areas for understanding.  difficult as this sometimes is, it is also highly rewarding.  I emerge from the process with a much richer understanding of what I am trying to teach, and ultimately my students are engaged in a richer and more meaningful educational experience.  They are no longer working their way from one Biblical verse to the next, from one Talmudic page to the following one, but rather they are tackling defined units of knowledge and seeking to master and understand them.

Much has been made about the motivational advantages of PBL.  I have always contended that people can only be motivated, at least long-term, to do something that they feel that they can understand and can be successful doing.  A student with a great memory can perhaps be motivated to memorize lists of facts and dates and names.  But any student can potentially be motivated by the opportunity to not only seize control of their learning, but to do so in a way where the path to mastery lies clearly before them.