Jim Love, Jack, 1971. Steel and Paint. Jacks, originally known as “knucklebones” (named for a game that used the bone in the ankle of sheep), is a game of ancient origin. This playful sculpture of the modern toy conjures up a variety of mathematical observations. At about 10 feet tall, what is the scale factor? What diameter ball would be appropriately scaled to this sculpture? What height person would be appropriately scaled to this sculpture? How many right angles are contained in the sculpture? How many angles of rotation are there? About how much does the sculpture weigh (one cubic inch of steel is about 0.28 pounds)?