Many times, visual descriptions help us communicate concepts that may be difficult to understand through narrative text alone. Visual system diagrams or concept maps are two means of adding value to the messages you are sharing. A concept map is a type of diagram that shows various relationships between concepts. See the Wikipedia Concept Map entry for an expanded overview.
To learn how to create and format drawings in Google, please view the instructions on the Google support site.
Creating Diagrams or Concept Maps
Below is a YouTube video describing the basics of creating a Diagram or Concept Map using Google Drawing in Google Drive. The first part (about 30 seconds or so) is simply audio explanation, then the "video" part of the movie will come on and walk you through the process of creating a simple concept map.