A simile is a comparison between two different kinds of objects that uses words such as like, as, or than. The simile frequently points out a relationship that is not immediately apparent. Think about some of the similes you have probably heard in class - "She was as fragrant as a rose" is saying that she smelled good. "The light is brighter than a new penny" is saying that the light was clean and shiny.
Good luck going through your book and finding some similes for your assignment!