At Beam Bridge, visitors experience how the thickness of a beam relates to its stiffness by comparing walks across a beam on its edge and the same beam on its side. Walking on the beam both compresses and stretches the beam: there is compression in the fibers along the top of the beam and tension in the fibers along the bottom. The beam, on its edge, has twice as many fibers resisting the forces that make it sag. However, it has half the fibers to resist bending from side to side. The beam, on its side, has just the opposite qualities: it has half the fibers resisting the forces that cause it to sag, while twice the material to resists sideways bending.