I have taught hundreds of students Introductory Biology over the span of many years. Ihad finally achieved that comfortable security of having a ready-made set of lecture notes, volumes of exam questions banked away, pre-printed study guides, practice exams, and quizzes, and a sense of predictability regarding the course.
Strangely enough, I was also bored and bothered. Bored from lecturing about the same things year after year, and bothered because my lectures came across so dogmatically that I was failing to impart to the students the uncertainty of scientific inquiry and the satisfaction of finding solutions to problems. The fact that I was "in charge" of the course had been construed by my students (with my help) to mean that I was the "possessor of knowledge," the sole provider of information, and that they were the "cups to be filled to overflowing." The structure of the class prevented students from seeing that all this information in textbooks and in my lectures had been preceded by years of research and ongoing questioning. They did not see that I, the presumed "authority," was a learner also. Clearly a change for my course was in order. I wondered if engaging my students in a more cooperative learning endeavor might empower them to take a more active role in their survey of biology, and might, at the same time, infuse me with renewed excitement about the course.
A conference on Problem-Based Learning offered by the Center for Teaching Effectiveness (CTE) at the University of Delaware aptly coincided with my restlessness and search for a solution. I learned techniques for writing real-life problems, ways to deal with group dynamics, and principles of transforming a traditional lecture course into a group-centered problem-based learning (PBL) course. I was interested in PBL, but could I successfully apply these techniques to my class of 80 students, who were mostly inexperienced first-semester freshmen of varying backgrounds and abilities? There was only one way to find out, and it made me suddenly more excited about teaching Introductory Biology than I had been in several years.
I am now approaching my fourth semester of using PBL in a large class and have accumulated some tips which may make the adventure smoother for someone who wishes to try the method. First, I began in an ordinary classroom (one not designed for group meetings), and without teaching assistants or tutors, thus I knew I would have to manage all groups on my own in a somewhat chaotic setting. Consequently, I decided to retain lectures for about 80% of the classes and use problem-based learning for the other 20%, limiting the PBL to in-class sessions, rather than out-of-class meetings. This would allow me to maintain the organization and the structure which I presumed were necessary for PBL to succeed with a large class.
In addition to the importance of organization and structure to the success of PBL in a large class, I found that the design of the problem, and the evaluation procedure had to be considered carefully also. Problems are best if kept short and reasonably simple. This does not imply that they cannot be challenging, but they should address what you consider to be the most important concepts for the course, rather than a complex factoid of knowlege which digresses from the essentials. If doing the problem within one class period, incorporate a challenging "bonus" question at the end which is open-ended -- this gives fast groups a challenge to work with while slow groups are finishing the required work. Designing a problem that can be addressed during class time, using the text as primary reference, keeps the groups in relative synchrony with one another, making it easier to monitor all 20 (or more) by yourself.
Your methods for evaluating work done through PBL sessions should be communicated clearly to the class at the beginning of the course. What percentage of the final grade will be from PBL? What type of group product will be expected from each problem session? Will individuals be graded as well as groups? Some suggestions:
In conclusion, using PBL in a large class requires attention to detail, organization, and some built-in structure which may not be necessary with a smaller class. The additional time involved for you, the instructor, pays off handsomely in the enhanced rapport which you establish as a co-learner with your students. Learning will become more of an active endeavor for students, rather than just for you, the instructor. Students will interact much more with one another than they would in a traditional lecture course, and a feeling of cooperation rather than competition should pervade the classroom. And you will never be bored - there are always new problems to research and write, and old problems to refine. New groups of students have ways of re-inventing solutions from new perspectives - your class will become a section of actively engaged creators-of-ideas rather than docile, passive recipients-of-knowledge.