I teach both high school chemistry and biology. In both cases, wikis can be used for both small and large group projects. Some research projects contain so many parts that it is sometimes necessary to have the students work in parts and then bring the ideas together in order to make sure all students have grasped the concept. Rather than have the students work together to create paper drafts during class on a research topic, I could instead have the students discuss their findings and create individual and groups summaries of their ideas or findings. Since some students can be reluctant to engage each other in face to face conversations and debates in class, this may serve as a safe zone to voice opinions and ideas. In addition, they would not be restricted to working only during class or when it is convenient for all to meet.
The projects would start off as large group projects which eventually whittle down to small group and then individual wiki projects. At first, I would use the wiki to allow students to provide feedback, support, and constructive criticism for class projects. In my vision, all students perform individual research on a particular question and post their ideas on the wiki. They would then work as a class to refine the idea. By providing the class with a project, the wiki can be used to separate the project by tasks, having smaller groups responsible for particular parts. For example, one group would be in charge of finding resources, another figures and diagrams, and yet another for editing. Some students would be in charge of summarizing the data into a coherent set of ideas, and others for formatting in APA. As the year continued, student groups would be rotated, allowing students to each fulfill a role in creating a properly researched investigation model. This would allow students to hone skills and model what is both good and bad about producing a group wiki. In doing so, they can develop individual skills so that they can ultimately create individual wikis that can be peer critiqued and edited.
Another idea would be to create a wiki for class notes, vocabulary, and study guides. After posting some guiding questions, students could work together to create a comprehensive resource for their studies in the classroom. This will allow them to teach other as well as encourage students to teach themselves. By having the students work on this a little bit each week, by the time testing rolls around, they will have a student created study resource to use to prepare.