"This site enables opera companies and educators to access and download FREE digital versions of the Opera for Everyone series of CDs and the Teaching Manual for teaching purposes. Our objective is to have these materials used to introduce everyone to opera -- the remarkable combination of music, drama, dance and the visual arts. Opera for Everyone provides an excellent opportunity for students and educators alike to become familiar with the background and music of four classic operas -- each related to a different important period of opera: Rossini's The Barber of Seville (1816); Verdi's La Traviata (1853); Bizet's Carmen (1875); and Puccini's Madama Butterfly (1904).
You may need to edit some parts. I have not listened to all of them yet.
Here are some other links to aid you in your opera studies:
Opera Plot Summaries
Listen to famous Opera pieces:
one step at a time...