Give a jigsaw piece to each participant. Ask them to walk around the room and find other people in the group with pieces of the jigsaw that go with theirs. Eventually the various members of the small groups join up and match up their pieces to make the picture, and they become a group. Think about your event objective and any particular themes: environment; gender; community relations; unfair trade; this can determine the jigsaw you will use.
Equipment: Set of jigsaw pieces (different one for each group). You can also use a photo or picture cut up.