When students have analyzed their assigned documents, assemble each group (of three pairs) together. Arrange for each pair of students to share its document analyses with the other group members using a placemat strategy. Provide each group with a large sheet of paper. Ask students to draw a circle in the centre with one wedge-shaped space for each pair of students.
Invite students to use their allotted space on the chart to record the key pieces of evidence from their documents for each of the causes. Once all students have summarized their ideas, direct each group to write the four main causes in the centre of the circle. Invite the groups to discuss the most significant evidence from each pair of students related to each of these causes. Explain that students will shortly be asked to reach their own conclusions about the relative importance of the causes, but for the time being they are simply to record in the centre of the circle key evidence that the group can agree on for each cause.