Was this the one where you make up a certain size block (10.5" would take 5 strips). Take 2 of the block, place right sides together, sew around the outside, and then cut into quarter square triangles? You press the quarter square triangle open, and reassemble the blocks so that the stripes are pointing in different directions.
Another good size for making with strips would be 13.5" - 14" (42"/3).