There is a temptation with using a tool like the wiki for teachers to simply introduce the tool and ask the students to use it, and then watch to see what happens. That usually occurs because teachers themselves are unfamiliar with the actual potential of the tool to the process of teaching and learning. While knowledge around this is still growing, we do know from teaching in general that students respond poorly to badly designed assignments with no real purpose articulated as to their connection with the learning outcomes or direct benefit to the student's overall learning experience.