I like these exercises because I was allowed to delete, move, split and merge features on a copy of a city geodatabase. Here is some features that has been modified.
I like the way I use the sketch tool from the editor toolbar to connect water lines that actually are connected in this city subdivision. I can see why you had to digitize these water lines. I guess if something like a new firehydrants was added to a new development, the city would need add it or those to their geodatabase.
I found that chapter 13, Projecting Data in Arc Map pretty interesting. I didn't know that map projections flat's the earth. So I guess from what I read and the exercises I did, using longitude and latitude defines the coordinates on a curve surface. Then when using a map, you would use the X and Y coordinates to define location.