Three straws make a triangle only when the two shorter ones add to more than the longest. Three fixed sides make exactly one triangle, three corners that add to 180 degrees make many sizes of the same shape, and some sets of measures make none at all. A flat or upright cut through a box shows a rectangle, and a cut through a pyramid shows a square or a triangle. The crew builds the roof frame from straws and slices clay blocks at the Blueprint Table.