At the crime scene, you have completed the initial walk-through and are planning your collection of the evidence at the scene, when a new investigator approaches you and asks about the differences between individual and class characteristics of physical evidence.
"Didn't they teach you this at the academy?" another investigator mutters under her breath.
The new investigator looks sheepish, but you assure him that you will get him up to speed regarding these characteristics of physical evidence. In this assignment, you will explain to the new investigator the differences between class and individual characteristics of physical evidence.