Reading Number 4, Ching goes into vivid detail on Structural elements and how they function, He tells us about elements like Structural spans and how long certain materials can be able to span as a beam, Structural patterns which allow us to use grid lines and critical points to indicate columns or load bearing walls, lateral stability  which tells us that while a building is being built it must be able to not only resists vertical loads like gravity but also have the ability to resist things like wind and seismic forces for any direction he tells us supports can be made by using things like rigid frames, shear walls and braced frames which can range from Timber/ Steel/ Reinforced concrete. During the beginning of the reading changes states that a structural unit has to have a structural system which also has to consist of things like columns, beams, slabs etc.