Active/Passive Overview

Active Sentences:


The professor                           teaches                     the students
Subject                                     Verb                        Object
(Doing actions)                                                        (Receiving actions)




Passive Sentences:
The students                            are taught                by  professor                  
Subject                                    Passive verb                  Object
(receiving actions)                                                       (doing actions)


Active/Passive overview: http://www.englishpage.com/verbpage/activepassive.html