Preterite Situations
• the beginning of an event
• the ending of an event
• completed action
• a series of completed actions
• a sudden change of any kind
• immediate or instantaneous actions
• an action or event that happened at a specific time in the past
• an action that happened for a specific amount of time
• an action that interrupted an action that was already going on
• describing something specific in the past

Imperfect Situations
• habitual or repeated actions
• simultaneous actions
• emotional or physical description
• actions already in progress
• background information to a story
• time
• stating date and year
• the day
• stating age
• setting and imagery in a story
• general description in the past

RESOURCES:
http://cla.calpoly.edu/~wlittle/span104/cap10/pretvsimper.html

http://bib.cervantesvirtual.com/servlet/SirveObras/35761630101354941976613/p0000004.htm#22

http://legacy.lclark.edu/~benenati/pretimp/pretimp.html