One of the most common shapes in structural design is the rectangle. All around us, from floor to ceiling, in doorways and in window frames, columns and beams are attached at right angles to form rectangles of different dimensions. Despite its prevalence, the rectangle is not a particularly strong shape. The compressive force of a weight pushing down can easily cause a rectangle to deform -- to change into a parallelogram -- if the structure's joints pivot. This means that all of a square's stability is provided by the strength of joints.

In contrast, the triangle is an inherently strong shape. It cannot be deformed unless the length of a side changes or one of its joints breaks. This makes the triangle one of the most rigid and stable shapes used in construction today. In fact, rectangular parts of structures can be strengthened by adding supports that form triangles within the rectangle, either at the joints or diagonally across the entire figure.

In building their newspaper chair, the ZOOM cast members made good use of triangles, connecting joints with diagonal supports that strengthened and stabilized the square shapes they started with. In addition, the newspaper tubes they used to build their chair were both strong and easy to make. Like triangles, tubes provide a great deal of strength. At the same time, they are much lighter than supports made of solid material.