Procedure

1. Decide which information on a topic students will compare and how many total items there are.

2. Instruct students to draw a circle on a piece of paper for each item, or pass out a pre-prepared handout. It is important that their circles overlap and that this area is large enough to contain notes.

3. Label each circle with the appropriate item. (For example, if students are comparing cats and dogs, they would label the left circle “Cats” and the right circle “Dogs.”)

4. Have students, individually or as a whole group, list unique information that applies only to that item in the non-overlapping section of the circle. 

5. Never have students brainstorm a list of shared characteristics in the overlapping spaces. If there are more than two circles, have them write down commonalities between two items in the area where those two circles overlap.

6. In the area where all three circles overlap, students should list things all three items have in common. (For example, if students add a bird in the comparison begun earlier, the overlapping space between the cat and dog might include “fur.” However, students might include “pets” in the space where the cat, dog, and bird circles overlap.)