From reading #4 from Building Construction Illustrated I have learned about wood, concrete, steel and masonry structural systems. I really liked how the book uses the illustrations to show the details of connection for each particular system, so we are able to understand how these are working. When skimming through the reading for the first time I was able to see that steel system is laid out differently that wood just by looking at the illustrations. It was clear to understand that wood beams are stacked on the girders while steel beams are aligned to the girders and welded. This chapter was also very important to understand our second drawing assignment. From this reading I started to understand how to estimate the span, depth, and width for the structural elements in each system. Also I have learned that the systems can be combined togetherness as the steel can be used for girders and beams, and precast concrete for the floor system. I believe this is a very important chapter to understand by young designers, as understanding these systems help to laid out and make use of structural grid.