A frequent criticism of PBL is that when students work in groups some will "slack off" or sit back and let the others do all the work. Anne Shaw recommends that teachers always build into the structure of the PBL curriculum an organizational strategy known as Jigsaw and Expert Groups. This structure forces students to be self-directed, independent and to work interdependently.
This means that the class is assigned (preferably randomly, by lottery) to Expert Groups. Each of the Expert Groups is then assigned to deeply study one particular facet of the overall project. For example, a class studying about environmental issues in their community may be divided into the following Expert Groups:
Air
Land
Water
Human impact on the environment
Each Expert Group is tasked with studying the materials for their group, taking notes, then preparing to teach what they learned to the rest of the students in the class. To do so, the class will "jigsaw", thus creating Jigsaw Groups. The Jigsaw Groups in the above example would each be composed of one representative from each of the Expert Groups, so each Jigsaw Group would include:
One expert on Air
One expert on Land
One expert on Water
One expert on "Human impact on the environment"
Each of these experts would then take turns teaching the others in the group. Total interdependence is assured. No one can "slack off" because each student is the only person in the group with that "piece" of the information. Another benefit is that the students must have learned the concepts, skills and information well enough to be able to teach it and must be able to assess (not grade) their own learning and the learning of their peers. This forces a much deeper learning experience.
Anne Shaw recommends that when students are teaching each other they also participate collaboratively in creating a concept map as they teach each other. This adds a significant dimension to the thinking and the learning. The students may build upon this map each time they Jigsaw. If a project is scheduled to last over the time period of six weeks the students may meet in their Expert Groups twice a week, and then Jigsaw twice a week, building upon their learning and exploration of the topics over time.
Once all the experts have taught each other, the Jigsaw Group then designs and creates a product to demonstrate what they now know about all four aspects of the PBL unit - air, land, water, human's impact. Performance-based products may include a wide range of possibilities such as dioramas, skits, plays, debates, student-produced documentaries, web sites, Glogsters, VoiceThreads, games (digital or not), presentations to members of the community (such as the City Council or a community organization), student-produced radio or television program, a student-organized conference, a fair, a film festival.
Students are assessed in two ways:
Individual assessments for each student - may include research notes, teaching prep notes and teacher observation. Other assessments may include those assigned by the teacher, for example, each student in the class must write an individual research paper for a topic of their choice from within the theme of the overall PBL.
Group assessments - each Jigsaw group creates and presents their product, preferably to an audience other than the teacher or their class.