Well you have your group together. Let's start handing out parts of the assignment to everyone-

Hey, where'd this kid go?

The Shadow is the group member who is almost never there to share information with the group. They're absent a good portion of the project and almost never show up until the day that the project is due. Now, depending on the circumstances and personality of the student, this may not be entirely this group members fault. Especially if the project takes place in winter, sometimes group members gets very sick, have to go to a funeral, or are absent for some other reason. Other times, they may just be trying to skip school, but it's usually up to the discretion of the rest of the group to figure out what this member's deal is.....