Yarn or (thick) Ribbon
Construction Paper (multiple colors)
Step One: Cut out a medium-sized triangle, then use it as a template to cut out five more.
Step Two: Using a different color, cut out circles or thick lines. Place them on a triangle, then glue. Decorate two or more of the triangles with various shapes. (I tried circles, but they didn't turn out too well...)
Step Three: Once the glue has dried, turn all your triangles over. Put them in the order you want them to hang, then place yarn or ribbon on them, near the top. Using a small piece, duct tape the yarn/ribbon to the triangle.
Step Four: Hang your banner!