For these readings, Ching goes in depth on how certain materials is used for construction , as well as their general purpose/rules of thumb. The materials explained in these readings were bricks, steel, wood, concrete, and stone. Wood is identified as softwood or hardwood, and are graded differently depending on how they were cut. Each wood are also considered as yard lumber or factory and shop lumber. Usually yard lumber is used for general building purposes, and factory/shop lumber is used for doors, windows, and mill work. Each piece has a grade-mark that indicates its stress grade,  origin, moisture content, when it was made, and type of lumber. There are many steel shapes,  and the one used frequently for columns are the W-shaped steel. There are other steel shapes, such as a round pipe, rectangular/square tubing, welded plates, and a cruciform. Ching also explains the spacing for various steel tube sizes. The rule of thumb for steel for estimating the depth of steel is span/20 with beams, and span/15 for girders, with a width 1/3-1/2 in. The idea of steel is to use the lightest steel that resists bending/shear forces. For concrete beams, the rule of thumb for depth is span/16, while the beam width is also 1/3-1/2 in. Some concrete parts require reinforced steel to help stability against forces. Concrete columns spacing determines what load could be on top of it. Concrete wall are usually used for loads as well, along with some reinforced steel. Precast concrete beams, and slabs are made with lightweight concrete which makes them better for structural efficiency, with less depth, reduced length and longer spans. Concrete topping is crucial because it increases fire-resistance, and could help out with wiring. The tees, and slabs of concrete varies depending on the load on top. Concrete girders are usually built for bridges or highways, but could be implemented in buildings sometimes. Masonry bricks vary in size, and depending on how they are used, they could be labeled as something different each time. The stretcher is a unit that is horizontally long, a header is a unit that is horizontal but is` laid out parallel  to the surface, a rowlock is a horizontal brick with a longer edge exposed on the face of the wall, and a soldier is a vertical brick with the longer edge face exposed. The way they are laid out each have a specific purpose, and is usually built for that reason. there is a running bend wall, a common bond, a stack bend, a Flemish cross/ diagonal, and many more.